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ANALYSIS OF PAINT ANDVARNISH PRODUCTS

BY

CLIFFORD DYER HOLLEY, M.S., PH.D.

CHIEF CHEMIST ACME WHITE LEAD AND COLOR WORKS

FIRST EDITIONFIRST THOUSAND

NEW YORK

JOHN WILEY & SONS

LONDON: CHAPMAN & HALL, LIMITED

1912

COPYRIGHT, 1912,

BY

CLIFFORD DYER HOLLEY

Stanbopc jprcss

F. H. GILSON COMPANYBOSTON, U.S.A.

PREFACE.

AN extended experience in the mixed paint industry

and in the manufacture of white lead and other lead

products has convinced the author that there is need

of a more comprehensive work on the analysis and val-

uation of paint products than has hitherto appeared.

The enactment of various laws regulating the sale

of prepared paints and the discussions arising there-

from have done much to stimulate chemical analysis

and research work with the various paint products.

New combinations have been brought to the attention

of the consumer, who must rely on the chemist, official

or .private, for their valuation and suitability for use.

The rapid development of the industry and the in-

creasing sharpness of competition has placed an added

responsibility upon the paint chemist of to-day; his

methods must not only be accurate, but must also be

capable of securing results with the greatest possible

rapidity.

It has been the endeavor of the author to present in

this volume such methods as he has found accurate

and at the same time rapid and convenient. A con-

siderable number of the methods are substantially the

same as those given in his earlier work,"Analysis of

Mixed Paints, Color Pigments, and Varnishes." The

scope of the work has, however, been greatly enlarged,

a large number of new methods have been introduced,

with many new paint products, whose properties are

discussed, while a large amount of data relative to the

263608

vi PREFACE.

composition of the various paint specialties to be found

on the market, has been included.

The author wishes to express his appreciation for

the assistance given him by his many friends in the

preparation of this work.

CLIFFORD D. HOLLEYDETROIT, MICHIGAN,

April 12, 1911.

CONTENTS

PAGBINTRODUCTORY CHAPTER. THE PROPER LABELING OF PAINT

PRODUCTS 1CHAP.

I. SEPARATION OF VEHICLE FROM PIGMENT 4

II. ESTIMATION OF WATER IN PAINTS 11

III. WATER EMULSIONS AND EMULSIFIERS 17

IV. ESTIMATION OF LINSEED OIL AND ITS ADULTERATIONIN MIXED PAINTS 23

V-. DETERMINATION OF THE PURITY OF LINSEED OIL ... 32

VI. DETERMINATION OF THE PURITY OF LINSEED OIL (Con-

tinued) 42

VII. ANALYSIS OF THE VOLATILE OILS 51

VIII. TURPENTINE THINNERS 59

IX. TURPENTINE SUBSTITUTES 72

X. THE INERT PIGMENTS 77

XI. ANALYSIS OF WHITE LEAD 92

XII. ANALYSIS OF SUBLIMED WHITE LEAD AND THE ZINC

PIGMENTS 104

XIII. ANALYSIS OF SUBLIMED WHITE LEAD AND THE ZINC

PIGMENTS (Continued) 116

XIV. DETERMINATION OF FINENESS, COVERING POWER AND

TINTING STRENGTH OF PIGMENTS 124

XV. THE PRACTICAL TESTING Our OF PAINTS 129

XVI. ANALYSIS OF WHITE PAINTS 143

XVII. ANALYSIS OF WHITE PAINTS (Continued) 153

XVIII. KALSOMINE, COLD WATER PAINTS AND FLAT WALLFINISHES. 163

XIX. COMPOSITION OF COLORED PAINTS 170

vii

viii CONTENTSCHAP. PAGE

XX. ANALYSIS OF INDIAN REDS, VENETIAN REDS, TUSCAN

REDS, RED OXIDES AND OCHRES 175

XXI. ANALYSIS OF BLACK PIGMENTS AND PAINTS 185

XXII. ANALYSIS OF BROWN PIGMENTS AND PAINTS 196

XXIII. ANALYSIS OF BLUE PIGMENTS AND PAINTS 204

XXIV. ANALYSIS OF YELLOW, ORANGE AND RED CHROME

LEADS, ANALYSIS OF VERMILIONS 211

XXV. ANALYSIS OF RED LEAD, ORANGE MINERAL AND

LITHARGE 221

XXVI. ANALYSIS OF PAINTS FOR MANUFACTURING PUR-

POSES 227

XXVII. COMPOSITION AND ANALYSIS OF FILLERS 233

XXVIII. SHINGLE STAINS, BARN AND ROOF PAINTS 236

XXIX. ANALYSIS OF JAPANS AND DRIERS 239

XXX. ANALYSIS OF SHELLAC AND SPIRIT VARNISHES 245

XXXI. ANALYSIS OF OIL VARNISHES 257

XXXII. THE PRACTICAL TESTING OF VARNISHES 269

XXXIII. VARNISH STAINS AND COLOR VARNISHES 279

XXXIV. ENAMELS AND VARNISH SPECIALTIES. . 282

ANALYSIS OF

PAINT AND VARNISH PRODUCTS

INTRODUCTORY CHAPTER.

THE PROPER LABELING OF PAINT PRODUCTS.

1. Let the label tell the truth. It is indeed unfor-

tunate that large quantities of ready-mixed and paste

paints are sold to-day more on the strength of the

vigorous advertising conducted by the manufacturers

than on the merit of the products themselves. The

extravagant claims of the manufacturers and the manyinstances of detected fraud have aroused the consumer

to the need of adequate protection. To this end nu-

merous state paint laws have been enacted requiring

the composition of each paint product of whatever

description to be printed on the label. This procedurehas been met with vigorous opposition on the part of

the paint manufacturers, who claim that they are thus

compelled to reveal valuable trade secrets. Such, how-

ever, is not the case, as in no instance has it been found

necessary to place on the label, in order to complywith the various laws, any information but that which

a competent chemist could ascertain with ease.

2. Fraud confined to certain classes of paints. Acareful examination of the situation will show that

fraud and abuse have been confined almost without

exception to white leads so called, paste paints, and

ready-mixed house and barn paints; in other words, to

1

2 ^ PAINJ.AND VARNISH PRODUCTS.

paint products in which varnish is not an essential

constituent. The various paint specialties, such as car-

riage paints, enamel paints for various purposes, etc.,

are of such a nature that the manufacturer cannot

afford to take chances in exploiting an inferior article,

and he must manufacture, if he desires to be successful,

as good a product as he can for the price for which he

sells it.

It therefore seems unwise to surround with rigid

regulations a class of products with which no fraud

has been practiced and which is not readily susceptible

to fraudulent practice. It is only reasonable to be-

lieve that the lawmakers desired to regulate the sale of

such paint products as they were acquainted with and

which are the more common ones in everyday use; and

to require labeling as to composition of paints contain-

ing varnish as an essential constituent is going a step

beyond the possibility of practical enforcement and at

the same time is not justified by present conditions.

3. Necessity for labeling mixed paints. The practice

of labeling a low-priced mixture of barytes, whiting,

and zinc oxide as strictly pure white lead and claiming a

high degree of wear and durability for a mixed paint

containing considerable quantities of water, a large

excess of benzine, and a high percentage of extenders

like barytes, clay, whiting, etc., will not cease until the

sale of such products is regulated by law and the

purchaser is given ample opportunity of knowing just

what he is buying. Such combinations may have a

commercial value, but the selling price should be de-

termined accordingly, and chemical analysis can be

depended upon to show their probable service value.

Valuation of paints by analysis. It is indeed probablethat chemical analysis alone will not enable the pur-

INTRODUCTORY CHAPTER. 3

chaser to select the best wearing paint from amongseveral, if each is composed of white lead and zinc

oxide, with possibly a small percentage of inert pig-

ments, suitably ground in pure linseed oil, and a req-

uisite amount of turpentine drier added, even if the

percentage of the different constituents vary consider-

ably.

In such instances, however, the analysis will indicate

that the purchaser is at least securing a fair productfor his money, and if properly applied may be de-

pended upon to give satisfactory service. Also, if he

possesses even a moderate knowledge of the value of

paint ingredients, the placing of the analysis on the

can will enable him to select a paint the compositionof which is most nearly in accord with his ideas.

4. Placing an additional burden on the manufacturer.

Requiring all paint products to be labeled as to com-

position places an undue burden of expense upon the

manufacturer, which is by no means slight, owing to

the immense variety of his products, each of which is

likely to appear in several shades or colors. On the

other hand, requiring him to place the analysis on

paints, whether ready-mixed or in paste form, in which

varnish is not a necessary ingredient, involves a slight

cost only, and at the same time efficiently protects the

consumer.

CHAPTER I.

SEPARATION OF VEHICLE FROM PIGMENT.

5. Preparation of sample. If a dry color, and in

bulk, great care must be exercised in securing a uni-

form sample, which should be thoroughly mixed on

the mixing cloth. If the sample be a liquid paint in

the unbroken package, the brand, manufacturer, and

guarantee, or other statements of importance appearing

on the label, should be carefully recorded. The can

should also be examined for any evidence of leakage,

or any markings indicating the date of manufacture.

On opening the package the unfilled portion should be

ed by placing a straightedge across the top of

n and measuring with a ruler the distance down-

ward to the surface of the oil. The gross weight of

the package should also be recorded at this time.

6. Condition of sample. The clear oil portion should

be carefully removed wittfthe aid of a pipette or suction

flask, and the surface of the paste portion remain-

ing should be examined carefully for evidence of any

precipitation of the drier constituents, which will often

form a gummy layer on the surface of the paste. The

older the sample the more pronounced the precipita-

tion. The condition of the paste portion is readily

ascertained with a steel spatula, and the degree of

settling, hardening, and any separation of the coarser

particles due to poor grinding, should be noted.

7. Obtaining a uniform sample. The paste is then

completely removed to a larger can, known as the mix-

ing can, which should be kept solely for this purpose,4


and stirred until smooth. The reserved oil portion is

gradually added, with constant stirring, which should

be continued until the analyst is thor-

oughly convinced that the sample is

uniform in composition. The entire suc-

cess of the analysis depends upon secur-

ing a uniform sample, and more analyses

are incorrect because of carelessness in

the preparation of the sample to be an-

alyzed than from any other source.

8. Weight. The weight of the cleaned

can subtracted from the gross weight

gives the net weight of the sample. Thecan is then filled to the height occupied

by the sample, as noted above, with

water from a carefully graduated meas-

ure, thus giving the net volume of the

paint. The can is then filled to the

brim with a measured amount of water

and the capacity of the can recorded.

9. Separation of the vehicle. Muchdifficulty is often experienced in extract-

ing the vehicle from the pigment, due to

the fineness of the pigment particles andthe ease with which they pass throughthe walls of the extraction tubes. This

difficulty, however, may be avoided bythe use of the apparatus illustrated be-

low. The extraction thimble, contain-

ing a filter folded cylindrically, is dried

in the hot-water oven for thirty min-

utes, weighed, and 10 to 15 grams of the sample weighedinto it, extracted with ether for 24 to 36 hours, dried,

and weighed again. The loss in weight represents the

FIG. 2.

EXTRACTION

APPARATUS.

6 PAINT AND VARNISH PRODUCTS.

vehicle, and the residue remaining, the pigment, which

is reduced to a fine powder and kept tightly stoppered

until examined. Any casein or similar product in the

paint will remain unextracted by the ether and unless

detected will interfere with the proper analysis of the

pigment. With very finely divided pigments like Prus-

sian blue a thickly padded Gooch crucible may be

used; the successive extractions may be decanted into

it, using a strong suction and refilling the Gooch before

it sucks dry.

10. Extraction with acetone. If the paint contains

a considerable percentage of water the extraction can

be best accomplished with the use of a good grade of

acetone. Many chemists prefer a solvent prepared bymixing 50 parts benzol, 30 parts wood alcohol, and 20

parts refined acetone.

11. Removal of vehicle in quantity. Another methodof obtaining sufficient vehicle from a paint for the de-

termination of the volatile oils, the quality of the lin-

seed oil, etc., is to fill a tall cylinder with such of the

sample as is not needed for the water estimation (100

to 150 grams) and for obtaining the free pigment,

corking it tightly, and placing it in a tall copper can

filled with water heated to about 70 C. By reducingthe viscosity of the oil in this manner the pigment will

settle quite rapidly, and in 24 hours, if the temperatureis maintained at 70 C., sufficient oil may be siphonedoff with the aid of the suction pump.

12. Use of centrifuge. By far the most convenient

method of obtaining sufficient vehicle for examination

is by centrifuging the paint. In the average labora-

tory an electric centrifuge is the most convenient type.

The cylinders used may be of glass, but preferably of

aluminum, as the pressure on the ends is often severe


when the centrifuge is in motion. The bottoms of the

cylinders should be removable, being screwed onto the

cylinder. This permits of the easy removal of the pre-

cipitated paint and the rapid cleaning of the cylinders.

13. Balancing the cylinders. It is necessary that the

cylinders opposite one another be evenly balanced, and

it is always advisable to balance up the cylinders

on the scales before placing them in the centrifuge.

The cylinders should be tightly corked to prevent loss

by evaporation of the volatile thinners, and live steam

admitted into the centrifuge chamber sufficient to heat

the contents of the tubes to about 70 C. In the

majority of cases the pigment will be thrown out rap-

idly and cleanly and, by using a number of cylinders,

an ample amount of the oils may be easily obtained.

14. Power centrifuges. In the factory laboratory,

where steam pressure is always available, an ordinaryBabcock butter-fat test can be conveniently used, the

steam leakage into the upper chamber being sufficient

to keep the tubes warm enough to insure the rapid

precipitation of the pigment. The machine selected

for this purpose should be very strongly made. Oneof the safest and most satisfactory centrifuges on the

market is that illustrated in this connection (Fig. 3),

manufactured by the International Instrument Com-

pany, Cambridge, Mass.

15. CENTRIFUGAL FORCE IN CENTRIFUGES.


EXAMPLE : A cup, weighing 2 pounds, at a speed of

3000 r.p.m., would exert a stress of 4000 Ibs. on its

trunnions.

FIG. 3.

16. Cushioning of glassware. A rubber cushion

should be supplied for each tube. Place a little waterin the metal tube, insert the glass tube, press down,and allow the water to overflow the metal tube. If

SEPARATION OF VEHICLE FROM PIGMENT. 9

this care is taken in the matter of balancing pressures

and of cushioning there should be very little breakageof glassware.

17. Rapid separation of pigment. If only the pigmentis desired the separated oil may be poured off and

the precipitated pigment stirred up with benzine, cen-

trifuged, and the operation repeated once more. This

will insure the removal of practically all the linseed

oil, only a trace remaining. When dried the pigmentshould receive an especially careful mixing, as the

centrifuging causes the pigments to settle to a certain

extent according to their specific gravities.

18. Typical analysesl of white and gray paints from

the same manufacturers, showing the change in the

ratio of pigment to vehicle:

1Analyses by the author.


19. Ratio of pigment to vehicle. It is customary with

a large number of manufacturers to have one ratio

of pigment to vehicle for white paints and another

ratio for the tints. In some cases this is necessary,

owing to the low specific gravity of the tinting colors,

but in many instances where only one or two per cent

of color is added to the white base it is not necessary

materially to reduce the proportion of pigment.

CHAPTER II.

ESTIMATION OF WATER IN PAINTS.

20. Occurrence. A fraction of 1 per cent of water

may occur normally in the vehicle. A small percent-

age, 1 to 3 per cent, may be incorporated into the

paint by the manufacturer under the belief that it

secures better penetration when applied to surfaces

that are slightly damp, and also that it will preventthe pigment from settling and becoming hard in the

can. Oftentimes, however, large quantities are intro-

duced for the purpose of cheapening the product. Thewater may be added to the paint and prevented from

separating out by forming an emulsion with the oil bythe aid of an alkali, or by grinding it into the pigment,

using an adhesive, such as glue or casein. In the first

case the nature of the ash left on burning some of the

separated vehicle will indicate whether an alkali has

been used or not. In the second case the vehicle will

yield less than 1 per cent of water .when distilled with

a dry, inert substance such as sublimed lead, as the

water remains with the pigment.21. Detection. Water may be tested for qualita-

tively in light-colored paints by rubbing with a little

eosin on a glass plate. If water is present the paintwill take on a strong pink color, otherwise the color

will remain practically unchanged. If the paint con-

tains considerable coloring material, rendering the eosin

inapplicable, a weighed strip of gelatine may be im-

mersed in the paint for several hours. If water is

present the gelatine will soften and increase in weight,11


the adhering paint being removed by the use of petro-

leum ether and drying for a minute or two between

sheets of filter paper. An immersion of the gelatine

for 18 to 24 hours will show the presence of water in a

paint containing as little as 2 per cent.

22. Estimation of water with amyl reagent. This

method, worked out by the author in his laboratory,

has given excellent results, not only in mixed paints

but also in paste and semi-paste goods. The deter-

mination requires only a few minutes, and as the com-

bined water of the white lead is not driven off there is

no correction to be applied.

23. Preparation of amyl reagent. This method has

also given admirable results when applied to the de-

termination of water in rosin oil and in varnishes con-

taminated with water. The components of the amyl

reagent amyl acetate and amyl valerianate should

be as pure as possible, and unless of specified purity an

inferior grade is apt to be obtained which will yield

unreliable results. Fritsche Brothers, New York City,

have furnished the most satisfactory article the author

has been able to secure. The amyl acetate and vale-

rianate should be washed before mixing with at least

two changes of pure distilled water at room tempera-

ture. This can readily be accomplished in a large

separatory funnel. Washing with water will remove

practically all the impurities, and such as may remain

will be saturated at that temperature. The reagent

is prepared by mixing 5 parts of amyl acetate with 1

part of amyl valerianate.

24. Determination. About 100 grams of the thor-

oughly stirred sample of paint are weighed into a flat-

bottomed, 200-250 c.c., side-necked distilling flask.

Add 75 c.c. of the amyl reagent and with a gentle

ESTIMATION OF WATER IN PAINTS. 13

rotary motion secure a thorough mixing of the contents

of the flask. Connect with an upright condenser anddistill over about 60 c.c. of the reagent into a cylinder

graduated into tenths of cubic centimeters. When the

larger portion of water has passed over, the upper

portion of the flask should be warmed gently with the

naked flame, in order to expel the small portion of

moisture that will have collected on the sides of the

flask. The distillation should then be continued until

the requisite amount of reagent has distilled over.

The percentage of water can then be easily read off

from the graduated cylinder and the contents of the

distilling flask will be sufficiently liquid to insure easyremoval. With paints high in volatile oils the volumeof the distillate should be increased to at least 75 c.c.

25. Practical example. The following determination

with a paint of known water content indicates the

satisfactory nature and accuracy of this method.

White lead 115 gramsLinseed oil 40 grams

Turpentine 10 gramsWater 6 grams

were thoroughly mixed, introduced into a side-necked

distilling flask, 75 c.c. of the prepared amyl reagent

added, and the mixture agitated until of uniform con-

sistency. The following distillation figures were ob-

tained :


The same mixture without the addition of water gave0.3 c.c. of water when run as a blank.

Theoretical percentage of added water 3.51

Percentage of water obtained (corrected) 3 . 56

Toluene is preferred by some chemists instead of the

amyl reagent; its use for this purpose is not recom-

mended by the author as the results are almost inva-

riably low.

26. Estimation bf water by distillation with inert pig-

ment. This method has found a wide use among paint

chemists. It is best carried out by using a retort, the

neck of which forms the inner tube of a condenser, the

outside tube being a Welsbach chimney. One hun-

dred grams of the paint is weighed into an aluminumbeaker and mixed with a thoroughly dried, inert pig-

ment like silica or sublimed lead until it ceases to be

pasty, and then transferred to the retort, which is

heated in an oil bath, the water being collected in a

graduate calibrated to fifths of cubic centimeters.

Toward the end of the distillation, the temperature of

the contents of the retort being raised to 200 C., a

very slow current of air or illuminating gas is admitted

to the retort through a tube passing nearly to the

surface of the pigment. This will carry over the last

traces of moisture.

27. Use of illuminating gas. It is advisable to pass

the illuminating gas through a wash bottle containing

sulphuric acid, which not only serves to remove mois-

ture but acts as an indicator for the rate of flowing

gas. The heating should be continued for at least two

hours at the above temperature to insure the completeremoval of the combined water from the basic carbo-

nate of lead which may be present. This should be

ESTIMATION OF WATER IN PAINTS. 15

deducted from the total amount of water obtained by

multiplying the basic carbonate present by 2.3 per cent,

which represents the average per cent of combined

water in white lead.

FIG. 4. ESTIMATION OF WATER.

28. Combined water. It is impossible to remove the

combined water by this method without decomposing

part of the lead hydroxide of the white lead, as the

water of. combination begins to split off at 110 to

120 C., the total combined water being driven off at

150 C. with 6 hours heating with little or no loss of


carbon dioxide. An exposure of 4 hours at a tempera-ture of 175 degrees results in the loss of all the water

and a slight amount of carbon dioxide; at 200 degrees

an exposure of 2 hours is sufficient to remove all the

combined water and about one-quarter to one-third of

the carbon dioxide.

In each case a blank should be run in order to ascer-

tain that the inert pigment and illuminating gas are

free from condensible moisture.

The author believes that a current of air obtained bythe use of an aspirator is preferable to the use of illu-

minating gas, as with the latter there is the possibility

of the formation of water from the hydrogen of the

illuminating gas and the lead oxide present, if the tem-

perature is raised too high.

29. Analyses. Eighty mixed paints analyzed by the

author, white and gray shades, gave a water content

calculated on the basis of total vehicle, as follows:

Amount of Water. Number of Paints.

to 1 per cent 26

1 to 3 per cent 25

3 to 6 per cent 5

6 to 10 per cent 3

10 to 24 per cent 21

CHAPTER III.

WATER EMULSIONS AND EMULSIFIERS.

30. Occasionally it devolves upon the paint chemist

to determine the agents used for securing and main-

taining the emulsion of oil and water in paints and for

preventing the hardening of paste goods, such as com-

bination leads, etc.

31. Necessity of an emulsion. The use of water in

paints has been a much discussed question. The ma-

jority of paint manufacturers have maintained that

the addition of a certain, amount of water is essential

for the preparation of a high-grade paint, in order to

prevent the pigments from settling hard in the bottom

of the can, in which case there is much trouble and

difficulty experienced in"breaking up" the paint when

desired for use. As regards this contention the author

believes the manufacturers are in the right, that better

results are secured by the use of a small percentage of

water in a paint high in lead and zinc. The line of

demarcation, however, between the amount that can be

considered legitimate for this purpose and that which

may be considered as added for adulteration or cheap-

ening, is by no means well defined. The author's ex-

perience has led him to believe that the true purposeof the addition of the water is best served by using an

amount not exceeding 3 per cent of the vehicle present,

and that any amount in excess of 5 per cent may be

regarded as having been added for cheapening the

product.17


32. Impairment of service value. The addition of anyconsiderable percentage of water unquestionably re-

duces the service value of a paint, but it is more often

the materials used with the water to obtain the emul-

sion that cause the greater harm. Any substance

which is astringent in its action, or which will cause a

partial saponification of the oil, or bring about reac-

tions between the oil and the pigments present, mate-

rially reduces the wearing value of such paint, and the

author can only regard the addition of such substances

as willful adulteration.

33. Classification. We may therefore divide the emul-

sifying agents into two classes, those which are inert

and those which are more or less active.

The first class comprises such substances as:

Glue,

Casein (free from alkali),

Oleates of lead and alumina,

Turpentine,

Glycerine, and

Starch.

The second class:

Chloride of lime,

Sulphate of zinc,

Silicate of soda,

Carbonate of soda,

Caustic soda,

Lead acetate,

Borax, and

Phosphate of soda.

34. Glue and Casein. The presence of glue and

casein may be detected by heating a small portion

WATER EMULSIONS AND EMULSIFIERS. 19

of the pigment, secured by extraction with ether, in a

small porcelain crucible and noting the odor given off,

and comparing the same with that obtained by heat-

ing a mixed pigment to which a little glue or casein

has been added. The amount present may be deter-

mined by running a nitrogen determination according

to the Kjeldahl method and multiplying the nitrogen

content by 6.37. About 10 grams of pigment should

be used.

35. Oleate of lead. Oleate of lead is but rarely used,

as it is the most expensive of all emulsifiers. The

present methods for detection and estimation are

unsatisfactory.

36. Turpentine. Turpentine is by far the best emul-

sifier to use, as it is itself a normal constituent of paint.

The formation of a water-turpentine emulsion can best

be accomplished by grinding into a paste a non-settling

pigment like asbestine pulp (magnesium silicate) or

china clay with a little linseed oil, adding water and

turpentine. The following affords a base of uniform

consistency and composition which can be added to

any mix of pigments in any desired proportion :

\ 150 Ibs. China clay,

150 Ibs. asbestine pulp,

21 gal. water,

4 gal. linseed oil,

2 gal. turpentine.

A formula like the above possesses much merit, as

both china clay and asbestine pulp are especially

valued for their non-settling qualities and acting in

conjunction with the water will prevent any reason-

able combination of pigments from settling hard, even

when used in small quantity.


37. Glycerine. Glycerine and starch are often used

in conjunction with each other, not only for the pur-

pose of introducing water but to prevent the hardeningof paste goods, such as combination leads. The fol-

lowing working formula illustrates their use :

500 Ibs. white lead,

300 Ibs. zinc oxide "xx,"

150 Ibs. white mineral primer,

200 Ibs. barytes,

2 oz. ultramarine blue,

| Ib. glycerine,

1 Ib. starch (powdered),

15^ gal. linseed oil.

38. Chloride of lime. This product, while one of the-

most powerful emulsifying agents, is the most harm-

ful to use owing to its astringent action on linseed oil.

Just what the chemical reactions are which it enters

into are difficult to determine, and it is difficult if not

impossible to prove its presence in the majority of

paints in which it is used except as indicated by failure

to give satisfactory service value.

39. Sulphate of zinc. The evil effects of sulphate of

zinc have been fully discussed by the writer in his

work devoted to Zinc and Lead Pigments, ChaptersXVI and XVII; therefore they need not be discussed

here.

40. Carbonate of soda and caustic soda. These two

substances are perhaps more generally used than anyof the others. The conversion of a portion of the lin-

seed oil into a water-soluble soap necessarily results

in decreasing the life or wearing value of the paintin which the above ingredients may be used. Their

presence may be judged by incinerating a small portionof the vehicle and examining the nature of the ash

obtained.

WATER EMULSIONS AND EMULSIFIERS. 21

41. Acetate of lead. The use of acetate of lead as

an emulsifying agent cannot be commended. It acts

as an astringent on the oil, although its effect is prob-

ably not so severe if it is incorporated into the paint

subsequent to its passage through the mill as it would

be if it were added in the original mix. A warm mill

running under a suitable tension will cause any appre-ciable amount of acetate of lead to act vigorously on

the linseed oil, causing a more or less pronounced

hardening in the package as well as diminishing the life

of the paint.

42. Borax and phosphate of soda. These products are

usually used with carbonate of soda or caustic soda.

The following is a much used formula:

Phosphate of soda 6 Ibs.

Bicarbonate of soda 6 Ibs.

Water 40 gal.

Both of these substances can be detected by the well-

known qualitative tests.

43. Combination emulsifiers. Frequently a combina-

tion of several strong emulsifiers is used. The follow-

ing formula has had an extensive use by several large

manufacturers :

Chloride of lime 100 Ibs.

Zinc sulphate 25 Ibs.

Lead acetate 25 Ibs.

Carbonate of soda 225 Ibs.

Water 1200 gal.

Wood alcohol 30 gal.

The above materials are dissolved separately, the

solution of zinc sulphate and of lead acetate beingadded to the chloride of lime solution (hot), the soda

solution added, and finally the alcohol, which is added


for the purpose of keeping the paint in storage from

freezing in winter. The above solution will emulsify

excellently with equal quantities of linseed oil. Theuse of a formula of this type cannot be beneficial to

the paint.

CHAPTER IV.

ESTIMATION OF LINSEED OIL AND ITS ADULTERATION IN

MIXED PAINTS.

44. Separation of the volatile oils. The clear oil ob-

tained by settling or with the aid of the centrifuge is

weighed and introduced into a suitable-sized Erlen-

meyer flask connected with a rather large condenser.

The contents of the flask are brought to 130 C. bymeans of an oil bath, and a current of steam as dry as

possible is conducted through the oil. The volatile oils

rapidly distill over and are collected in a weighed, short-

stemmed, separatory funnel, the water being drawn off

from time to time as may be necessary. Severe froth-

ing during the distillation indicates that an emulsify-

ing agent, such as caustic soda or carbonate of soda, has

been used. The frothing can be overcome by the addi-

tion of a few cubic centimeters of dilute sulphuric acid

to neutralize the alkali used. The distillate is allowed

to stand for several hours to insure the complete sepa-

ration of the water, which is then drawn off and the

volatile oils weighed and bottled for subsequent exam-

ination. The aqueous portion of the distillate will in-

evitably carry with it a small quantity of volatile oil,

but the quantity will be slight, amounting to about 0.4

gram per 100 c.c. of water distillate. After obtaining

the percentage of volatile oil the linseed oil is calcu-

lated by difference, by subtracting from 100 the per-

centages of volatile oil and water present in the paint.

The linseed oil, after being freed from the volatile

oils, is allowed to stand, tightly corked, for several hours23


in a warm place until thoroughly settled, and may then

be tested for the presence of other oils.

45. Presence of driers. The linseed oil thus obtained

will contain the Japan or drier solids present in the

paint, which will usually be of a rosin nature. In the

cheaper class of paints, and especially when linseed

oil commands a high price, the manufacturer will often

obtain relief by the use of a liberal percentage of a

cheap benzine drier having a rosin base.

46. Specific gravity. Determine the specific gravity

by means of a pycnometer or a Westphal balance.

The specific gravity may be taken at room tempera-ture and calculated to 15.5 C.

Correction for 1 C. = .000650,

Correction for 1 F. = .000361.

The accepted limits for pure raw oil at 15.5 C. are

0.930 to 0.936 and for boiled oils 0.937 to 0.945. Alow specific gravity may indicate:

a. Mineral oils.

b. Cottonseed oil.

c. Corn oil.

d. Soya-bean oil.

A high specific gravity may indicate:

a. Rosin or resinous products.

6. Rosin oils.

c. China wood oil.

d. Excessive heating or unusual addition of driers.

47. Spot test. One or 2 c.c. of the oil are poured on

a porcelain plate and a drop of concentrated sulphuric

acid is added carefully. If pure, the spot formed will

bear a marked resemblance to a begonia leaf. If rosin

ESTIMATION OF LINSEED OIL. 25

or rosin oil be present a black, gummy mass immediately

results; cottonseed oil gives a spot without the char-

acteristic markings of the linseed-oil spot. Mineral

oils give a scum band, rapidly spreading out over the

surface from the drop, the margin of the band being

uniformly circular. Fish oils give a similar reaction,

but the margin of the band is not at all uniform and

may be readily distinguished from mineral oils. With

a little practice and working with oils of known com-

position this test can be relied upon to detect any

appreciable adulteration with the above oils.

48. Mineral oils. The spot test for petroleum prod-

ucts may be confirmed by allowing a sample of the

oil to flow down a sheet of glass the other side of which

has been painted jet black. If petroleum products

are present even in a minute quantity, the sample will

exhibit the "bloom" characteristic of mineral oils. Astandard sample should always be run for comparison.

It is possible to remove the" bloom" of mineral oils

by the use of nitrobenzine, nitronaphthalene, or similar

compounds, but the author is of the belief that this is

very seldom resorted to in the paint industry.

49. Quantitative estimation of mineral oil. Quantita-

tively the mineral oil may be estimated by saponifying

10 grams of the oil with alcoholic potash for 2 hours,

using a return condenser. The alcohol is distilled off

and the soap dissolved in 75 to 100 c.c. of water,

transferred to a separatory funnel, and 50 c.c. of ether

added. The liquids are then shaken, avoiding the

formation of an emulsion as far as possible. The

aqueous solution is then drawn off, the ethereal layer

washed with a few cubic centimeters of water to which

a little caustic potash has been added, and poured into

a weighed flask. The soap solution is then returned


to the separator, and twice extracted with ether in the

same way as before.

The combined ethereal solutions are distilled off on

the water bath, the flask dried and weighed. The in-

crease in weight represents the amount of unsaponi-fiable matter, and unless rosin oil is present, represents

the mineral oil with the exception of about 2 per cent,

the average amount of unsaponifiable matter in lin-

seed oil.

50. Separation of mineral oil from rosin oil. Themineral oil may be separated from the rosin oil in the

unsaponifiable material by heating 50 c.c. of nitric

acid of 1.2 specific gravity to boiling in a flask of

700 c.c. capacity, the source of heat removed, and the

unsaponifiable material added. The flask is then heated

on the water bath with frequent shaking for about one-

half hour, and 400 c.c. of cold water added. After cool-

ing, 50 c.c. of petroleum ether is added and the flask

agitated, the mineral oil is dissolved, while the resin-

ous matters remain in suspension. The liquid is then

poured into a separatory funnel, leaving behind as

much of the resinous material as possible. After set-

tling, the aqueous liquid is drawn off and the ethereal

layer poured into a weighed flask. Another portion

of petroleum ether is added to the rosin remaining in

the flask, and allowed to act upon it for about ten

minutes, when it is added to that in the weighed flask.

After distilling off the ether the oil is weighed. Min-eral oils lose about 10 per cent when treated with

nitric acid in this way, and hence the weight of the

oil found must be divided by 0.9 in order to find the

amount present in the sample analyzed.

5oa. The Outerbridge test for mineral oil and rosin oil.

A few drops of the oil to be tested are placed between


two plates of clear glass, placed against a black back-

ground and examined by reflected light from an enclosed

arc lamp, adjusted to show a faint rosy light in addition

to the powerful white light. The presence of mineral

oil is evidenced by a greenish fluorescence, and rosin

oil by a bluish fluorescence. Even the so-called de-

bloomed oils show up strongly under this test. Bypreparing a set of standards of known composition as

to percentages of mineral or rosin oils, and judging the

sample under examination by comparison, reducing it, if

necessary, with a known amount of pure vegetable oil

until it corresponds in fluorescence with one of the

standards, the approximate percentage of rosin or min-

eral oil may be determined. For this purpose 50 c.c.

oil test bottles may be used. The value of the test

depends on the enormously intensified fluorescence due

to the particular source of light employed.

51. Cottonseed oil. This oil is seldom found in

house paints, but is often used in the cheaper class of

barn paints. The spot test may be confirmed by the

Halphen test, the apparatus required being a large

test tube with a condensing tube and a brine bath;

the reagent employed being a 1.5 per cent solution of

sulphur dissolved in carbon bisulphide with an equalvolume of amyl alcohol added. Equal volumes of the

oil and reagent are heated in a steam bath at first, and,

after the violent boiling has ceased, in the brine bath

at 105-110 C. for about 30 minutes. As little as 1

per cent of cottonseed oil will give a crimson wine

coloration. Cottonseed oil heated to 250 C. does not

respond to this test.

Quantitatively, the amount of cottonseed oil can onlybe approximated in a very general manner by means

of the iodine values.


Let x = percentage of one oil and

y = percentage of the other oil,

m = average iodine value of pure oil x,

n = average iodine value of pure oil y, and

I = iodine value of sample under examination,

100 (7-

n)then x = * L *mn52. Corn oil. This oil gives a spot test much re-

sembling that given by linseed oil, but may be detected

in linseed oil, if in quantity, by the following test:

Dilute with four volumes of benzine, add one volume

of strong nitric acid, shake. Linseed oil turns a white

color, while corn oil turns a reddish orange.

Quantitatively corn oil can be estimated only ap-

proximately when in linseed oil, by the same method

used for cottonseed oil.

53. Fish oils. In addition to the spot test these oils

may be detected by rubbing a little of the sample

vigorously between the palms of the hands. Fish-oil

mixtures give the characteristic odor of oils of this

class.

54. In case of doubt the Eisenschyml test l may be

used: One hundred drops of the oil are dissolved in

6 c.c. of a mixture containing equal parts of chloroform

and glacial acetic acid. Bromine is added drop bydrop until the brown coloration remains. After 10 to

15 minutes the test tube is placed in a beaker contain-

ing boiling water. Linseed oil and other vegetable oils,

such as China wood oil, cottonseed oil, corn oil, etc.,

will clear up completely within a few seconds, while

fish oils will remain cloudy and precipitate an insolu-

ble bromide at the bottom of the tube after a short

1 J. Ind. and Eng. Chemistry, Feb., 1910.


time. With a little practice 5 per cent of fish oil is

clearly recognizable.

In the case of boiled linseed oil it is necessary to

remove the metallic constituents before adding the bro-

mine. This is preferably done by shaking with a 10

per cent solution of nitric acid saturated with potas-

sium nitrate.

In mixtures with linseed oil the amount present can

only be determined crudely, by means of the "rise of

temperature" with sulphuric acid with the Maumene

apparatus described under the analysis of the volatile

oils (Allen found the rise of temperature with sul-

phuric acid to be 104 to 111 in the case of linseed oil,

and 126 in the case of menhaden oil), or else by weigh-

ing the insoluble bromides according to the procedure

described by Eisenschyml. Fish oils are used only "to

a limited extent in paints.

55. Rosin and rosin oils. These products are best

detected qualitatively by means of the Liebermann-

Storch reaction, which is of sufficient delicacy to de-

tect the presence of even very small quantities of rosin

oil or rosin drier in boiled oil. Shake 1 to 2 c.c. of the

oil under examination in a test tube with acetic anhy-drides at a gentle heat, cool, pipette off the anhydride,

and place a few drops on a porcelain crucible; cover,

and add one drop of sulphuric acid (34.7 c.c. sulphuric

acid and 35.7 c.c. water) so that it will mix slowly.

If rosin or rosin oil is present a characteristic violet,

fugitive color results. Certain fish oils will give a very

similar color, but if present are easily detected by the

fishlike odor of the oil on warming.Old samples of pure boiled oil give a color that

might be easily mistaken for rosin or rosin oils; in such

cases it is best to warm the oil with alcohol so as to


extract the bulk of rosin present and test the alcoholic

extract. Rosin may be more completely separated andestimated by Twitchell's process (J. Soc. Chem. Ind.,

1891, 10, 804) or by Cladding's method (Amer. Chem.

J., 3, 416). This process depends upon the solubility

of silver resinate in ether, while the silver salts of fatty

acids are insoluble.

56 Soya-bean oil. This oil has come into use quite

largely during the last two years. Its chemical and

physical properties are so nearly like those of linseed

oil that it is difficult to detect it with certainty whenmixed with linseed oil. In such mixtures "the spot test

exhibits a yellowish-green fluorescent color which is

clearly recognized, but in the presence of a rosin drier

this reaction is masked. When used to adulterate lin-

seed oil an excessive amount of drier is usually added

in order to overcome the slow drying of the soya-beanoil. Unlike linseed oil it does not bleach when strongly

heated, but becomes several shades darker.

57. Constants of soya-bean oil.

Specific gravity 0.923-0.924

Acid number 190

Saponification number 188-188.5

Iodine number 127-136

Average iodine number 131

Often as much as 25 per cent of soya-bean oil maybe added to linseed oil before the iodine number will

be lowered sufficiently strongly to indicate such adul-

teration. However, if the iodine number is below 170

(Hubl) the presence of soya-bean oil may be strongly

suspected. The oxygen absorption test will also yield

information of value.

58. In the preparation of gloss paints a little varnish

is added, the gums of which might be mistaken in the


above tests for rosin. In the cheaper paints a large

excess of rosin is used in the resinate drier added. Aneasy method of detecting rosin and other resins and

estimating the relative amount present is to stir upabout 100 grams of the paint with 500 c.c. petroleum

ether, allow to stand 24 hours in a cold place, siphonoff the ether, and examine the skin formed on top of

the pigment. This will harden in the course of an-

other day so that it may be removed, placed on a

watch glass, washed free of adhering pigment with

more petroleum ether, and dried. The color and other

physical properties will enable one to judge whether it

is rosin or some of the other varnish gums.

59. China wood oil. The constants of China wood oil

run quite uniform. The Hanus iodine method gives

an iodine number abnormally high. The Hubl modifi-

cation yields the best results, a 6-hour absorption being

sufficient.

Specific gravity 0.941-0.943

Free acid value 4-4 . 5

Saponification number 190.8-191

Hubl iodine number 163-175

CHAPTER V.

DETERMINATION OF THE PURITY OF LINSEED OIL.

60. The paint chemist is frequently required to pass

on the purity and quality of linseed oil, both raw and

boiled, and must therefore determine its analytical char-

acteristics with much care. The following example rel-

ative to a pure raw linseed oil is illustrative of the data

usually required:

Specific gravity at 60 F. (15.5 C.) 0.9334

Iodine value 174 .

Unsaponifiable matter 1.1 per cent

Saponifiable value 191.8

Acid value 2.8

Rosin test NegativeTime of drying, 50 hours as against 52 hours

with standard sampleLoss at 100 C 0.10 per cent

Color, odor, and taste similar to standard.

The above determination can often be supplementedwith advantage by .data derived from the following

estimations :

Flash test. Oxygen absorption.

Maumene" figure. Bromination figure.

Refractive index at 15 C. Hexabromide test.

61. Specific gravity. The specific gravity of a raw lin-

seed oil should lie between 0.930 and 0.936, and that of

boiled linseed oil between 0.937 and 0.945. All adulter-

ants except rosin and rosin oil would lower the specific

gravity.

62. Determination of the iodine number. The newer

Hanus method for the estimation of the iodine number32

THE PURITY OF LINSEED OIL. 33

is to be preferred to the older standard Hiibl method,as the Hubl solution rapidly loses strength on standing

and is very slow in its reaction. Nearly every chemist

using it employs a modification of his own, especially as

regards the time for the solution to remain in contact

with the fat or oil, and hence very different results maybe obtained on the same oil or fat by different investi-

gators. Comparative tests by the two methods madein this laboratory gave results which varied only a few

tenths of one unit.

63. Preparation of reagents. Iodine solution. Dis-

solve 13.2 grams of iodine in 1000 c.c. glacial acetic acid

(99.5 per cent acid, showing no reduction with bichro-

mate and sulphuric acid) ;add enough bromine to double

the halogen content determined by titration 3 c.c. of

bromine is about the proper amount. The iodine maybe dissolved by the aid of heat, but the solution should

be cold when bromine is added.

Decinormal sodium thiosulphate solution. Dissolve

24.8 grams of chemically pure sodium thiosulphate,

freshly pulverized, as finely as possible and dried between

filter or blotting paper, and dilute with water to one

liter at the temperature at which the titrations are to

be made.

Starch paste. One gram of starch is boiled in 200 c.c.

of distilled water for ten minutes and cooled to room

temperature.Solution of potassium iodide. One hundred and fifty

grams of potassium iodide are dissolved in water and

made up to one liter.

Decinormal potassium bichromate. Dissolve 4.9066

grams of chemically pure potassium bichromate in dis-

tilled water and make the volume up to one liter at

the temperature at which the titrations are to be made.


The bichromate solution should be checked against

pure iron.

64. Determination. Standardizing the sodium thiosul-

phate solution. Place 20 c.c. of the potassium bichrom-

ate solution, to which has been added 10 c.c. of the

solution of potassium iodide, in a glass-stoppered flask.

Add to this 5 c.c. of strong hydrochloric acid. Allow

the solution of sodium thiosulphate to flow slowly into

the flask until the yellow color has almost disappeared.Add a few drops to the starch paste, and with constant

shaking continue to add the sodium thiosulphate until

the blue color just disappears.

65. Weighing the sample. Weigh about 0.5 gram of

fat or 0.250 gram of oil on a small watch glass or byother suitable means. With drying oils which have a

very high absorbent power 0.100 to 0.200 gram should

be taken. The fat is first melted, mixed thoroughly,

poured onto the crystal, and allowed to cool. Intro-

duce the watch crystal into a wide-mouthed 16-ounce

bottle with a ground-glass stopper.

66. Absorption of iodine. The fat or oil in the bottle is

dissolved in 10 c.c. of chloroform. After complete solu-

tion has taken place, 25 c.c. of the iodine solution are

added. Allow to stand with occasional shaking for

30 minutes. The excess of iodine should be at least

60 per cent of the amount added.

67. Titration of the unabsorbed iodine. Add 10 c,c. of

the potassium iodide solution and shake thoroughly,then add 100 c.c. of distilled water to the contents of the

bottle. Titrate the excess of iodine with the sodium

thiosulphate solution, which is added gradually, with

constant shaking, until the yellow color of the solution

has almost disappeared. Add a few drops of starch

paste and continue the titration until the blue color

THE PURITY OF LINSEED OIL 35i

has entirely disappeared. Toward the end of the reac-

tion stopper the bottle and shake violently, so that anyiodine remaining in solution in the chloroform may be

taken up by the potassium iodide solution.

68. Setting the value of the iodine solution. At the time

of adding the iodine solution to the fat two bottles of

the same size as those used for the determination should

be employed for conducting the operation described

above, but without the presence of any fat. In everyother respect the performance of the blank experimentsshould be just as described. These blank experimentsshould be made each time the iodine solution is used.

Great care must be taken that the temperature of the

solution does not change during the time of the opera-

tion, as acetic acid has a very high coefficient of ex-

pansion, and a slight change of temperature makes an

appreciable difference in the strength of the solution.

69. A freshly prepared linseed* oil will have an iodine

value of about 185 to 187; this will rapidly drop to

about 180, and when suitably aged will have decreased

to about 175, although an old oil may have an iodine

value as low as 170. This figure, however, should be

regarded as the lowest acceptable limit. Boiled linseed

oil as prepared for paint purposes will show an iodine

number ranging between 160 and 175. Specially boiled

oils may have an iodine number as low as 150.

70. IODINE NUMBERS OF VARIOUS OILS.

China wood oil 163-175

Cora oil 111-125

Cottonseed oil 101-117

Fish oil 148-180

Rosin oils 40- 65

Petroleum products 4-20Soya-bean oil 127-136

Turpentine 320-385

36 PAINT AND VARNISH PRODUCTS.A

71. Unsaponifiable matter. The method for determin-

ing the unsaponifiable matter has been stated in the pre-

ceding chapter. A raw linseed oil should not contain

more than 1.6 per cent of unsaponifiable matter and

may contain as little as 0.5 per cent. A boiled oil will

usually contain a slightly higher percentage, varyingbetween the limits of 1 and 2 per cent.

The unsaponifiable matter in linseed oil consists essen-

tially of waxes and complex alcohols.

72. Determination of the saponification value. This

value is also spoken of as the Koettstorfer number and

the saponification number. In each case it is equiva-

lent to the number of milligrams of potassium hydroxide

necessary to saponify one gram of the oil.

Two grams of the oil are weighed out into a small

Erlenmeyer flask and saponified with 25 c.c. of half-

normal alcoholic potash, by heating gently on a water

bath, a funnel being inserted in the flask. When the

saponification is complete a few drops of phenolphtha-lein are added and the excess of alkali titrated with half-

normal hydrochloric acid. A blank determination of

the strength of the alcoholic potash should be made at

the same time.

The saponification value of raw linseed oil should lie

above 189 and of boiled linseed oil above 197.

73. Determination of the free fatty acids in linseed oil.

Ten grams of oil are weighed into a suitable-sized Erlen-

meyer flask and 50 c.c. of neutral, aldehyde-free alcohol

added. The mixture is heated to about 60 C. for a

minute or two, then cooled and titrated with tenth

normal alcoholic potash, using phenolphthalein as an

indicator.

Oil made from moldy seed, or seed contaminated

with mustard oil, or oil containing rosin, will have a


high acid figure. Pure raw oil should have a low acid

figure; boiled oil will have a slightly higher figure.

74. Preparation of aldehyde-free alcohol for alcoholic

potash solution. Dissolve 1.5 grams of silver nitrate in

about 3 c.c. of water and add to a liter of alcohol in a

glass-stoppered cylinder, mixing thoroughly. Dissolve

3 grams of pure potassium hydroxide in 10 to 15 c.c. of

warm alcohol. Cool, pour slowly into the alcoholic

silver nitrate solution, without shaking. The silver

oxide is precipitated in a finely divided condition.

Allow to stand until the precipitate has completelysettled. Siphon off the clear liquid and distill. Thedistillate will be neutral and free from aldehydes, andwill not darken when used as a solvent for potash.

The acid value of raw linseed oil is between 1 and 5

and of boiled linseed oil between 4 and 12, averagingbetween 7 and 8. Rosin and rosin in oils, if present,

would materially raise the acid value, as rosin has an acid

value of from 120 to 150 and rosin oil from 20 to 50.

75. Free mineral acid. Any free mineral acid in

bleached oil is determined by washing a definite weightof oil with water, separating the water, and titrating the

dissolved mineral acid present. Any mineral acid found

will usually be sulphuric acid. Its presence is decidedly

objectionable.

Varnish oil. A specially refined linseed oil is used

in the manufacture of varnishes, and it often devolves

upon the paint chemist to pass on such oils. It is not

safe to judge the color of the oil from the sample as

received, but it should be heated in a beaker slowly, to

the temperature required in the varnish kettle, and

after cooling the color should be compared with the

standard sample, which should be kept in a dark

place. Some varnish oils will bleach considerably


under heat, and others slightly or not at all. Varnish

oils act on the varnish gums very differently in the

varnish kettle; some flux with the gum easily; others

combine with the gum with difficulty, requiring an ex-

cess of heat and a longer time to cook, often affording a

varnish of quite dissimilar properties. It is therefore

advisable for the chemist to have the varnish oil under

examination thoroughly tried out in the varnish kettle

before approving it.

76. Determination of the flash point of linseed oil. For

exact flash-point figures rather expensive and compli-

cated testers are needed, but for commercial tests that

yield approximately the same figures a very simple

apparatus may be used, consisting of a two-ounce cru-

cible, a thermometer reading at least 300 C., and a

small gas jet attached to a rubber tube, a flame about

the size of a pea being used. The cup is filled two-

thirds full of oil, the bulb of the thermometer suspendedin it, and the oil slowly heated. The determination

should be carried on in a place entirely free from drafts.

At short intervals the gas flame is brought close,

but without touching, to the surface of the oil, with a

slow, sweeping motion. The first distinct puff of pale-

blue flame that shoots across the surface of the oil in-

dicates the flash point of the oil, and the temperatureat which this occurs is noted.

Hurst states that linseed oil, whether raw or boiled,

flashes at about 243 C., but these figures are consider-

ably lower than those obtained in this laboratory, the

raw oils flashing in the vicinity of 300 C. and the pureboiled oils from 275 to 300 C. Volatile oils used in

the drier added to the oil lower the flash point consider-

ably, 4 or 5 per cent of volatile oil lowering the flash

point to about 250 C. The other vegetable oils, as


corn and cottonseed oils, flash at nearly the same tem-

perature as linseed oil. Mineral oils, such as would

be used for adulteration, flash at 193 to 216 C.,

rosin oils at 140 to 167 C. The presence of rosin oil

would also be indicated by the strong odor of rosin

given off during the heating. Benzine and turpentine

when present in linseed oil rapidly lower the flash point

according to the percentage present, having a flash

point themselves but little above that of room tem-

perature.

77. Correction to be applied to the thermometer reading.

Let N = Length of exposed thread of mercury ex-

pressed in degrees.

T = observed boiling point.

i = temperature of the auxiliary thermometer,

the bulb of which is midway between

the ends of the exposed mercury thread.

0.000154 = apparent coefficient of expansion of mer-

cury in glass.

C = the correction in degrees.

Then C = N(T -i) X 0.000154.

78. Linseed oil from inferior seed. This includes oil

prepared from impure or adulterated seed, giving an

oil of inferior quality, or, what is essentially the same

thing, the screened foreign seeds are separately crushed

and pressed and the resulting oil used to blend with a

pure linseed oil. Such oils dry slowly and imperfectly,

and the resulting film lacks the" hardness" given by

the pure oils, and often give the consumer as just cause

for complaint as the more grossly adulterated varieties.

79. When sold as raw oil, such oils usually have a"

greenish tinge, which disappears or is masked in the

boiling. Chemically this form of adulteration is more

difficult to detect than when other oils of distinctly


different chemical properties are used. With this class

of oils the specific gravity, iodine number, saponifica-

tion value, and unsaponifiable matter remain nearly

normal, and the leading tests that may be applied to

such suspected oils are their oxygen absorption powerand the time required for drying. Both the per cent

of oxygen and the rate of absorption will be found

markedly lower, depending on the amount of foreign

seed oil present. In order to obtain comparable re-

sults, a standard oil of known purity should be carried

through the tests along with the suspected oil, as the

weather conditions may seriously affect the rate of

drying.

80. Spread about one gram of precipitated lead,

weighed off accurately, on a somewhat large watch

glass in a thin layer, and then allow to fall onto it from

a pipette 0.6 to 0.7 gram (not more) of the oil to be

tested, placing each drop on a different portion of the

lead and taking care that the drops do not run into one

another. Then allow the watch glass to stand at the

ordinary temperature in a place exposed to light and

protected from falling dust. Weigh at frequent inter-

vals in order to note the rapidity with which the oil

is absorbing oxygen and to determine accurately whenthe oil ceases to gain weight. The lead powder is pre-

pared by precipitating a lead salt with zinc, washingthe precipitate rapidly in succession with water, alco-

hol, and ether, and finally drying in a vacuum.

81. Instead of precipitated lead, thin aluminum

plates 3 inches by 6 inches may be used. The plates

are weighed and 0.1 gram or 0.2 gram of oil rubbed

over the plate, giving a thin, uniform film, weighed, set

aside in a dust-free place, and the increase in weightnoted from time to time.


The oxygen absorption figure of a freshly preparedlinseed oil is usually between 18 and 19 per cent. This

percentage will diminish somewhat during the aging

process, but should not go below 16. On the other

hand, a boiled oil may have an oxygen absorption as

low as 14 per cent but will average about 16 per cent.

The oxygen absorption of oils added as adulterants

and weed seed oils which may be present decrease the

oxygen absorption value.

82. Composition of linseed oil foots.1 The foots from

linseed oil, manufactured by the naphtha extraction

process, after centrifuging, contained 75.8 per cent lin-

seed oil, the extraction being conducted with carbon

disulphide. The insoluble portion contained:

Per cent.

SiO2 34.38

CaO . . .:.,-.; . ; 7.98

MgO 8.39

P2O5 46.50

K2O Present

97.17

The foots from an hydraulic pressed linseed oil

contained :

Per cent.

SiO2 NoneCaO 3.26

MgO 4.99

K2O 10.27

P2O 6 81.08

99.08

1Eisenschyml, J. Ind. and Eng. Chem., Jan., 1910,

CHAPTER VI.

DETERMINATION OF THE PURITY OF LINSEED OIL

(Continued).

83. Determination of the bromine absorption figure,

Mcllhiney's method. 1 The advantage of this methodis that the absorption of halogen by addition is deter-

mined separately from the absorption by substitution,

resulting in additional information as to the nature of

the substance.

The process as at present used is as follows: A quan-

tity of the oil to be analyzed is weighed into a glass-

stoppered bottle, 10 c.c. of carbon tetrachloride added

to dissolve the oil, and 20 c.c. of third-normal bromine

in carbon tetrachloride added from a pipette. It is

not found necessary in filling the pipette with bromine

solution to use any special arrangement to prevent the

introduction of bromine vapor into the mouth. Only a

rubber tube is necessary. Another pipette full of solu-

tion should be added to 10 c.c. of carbon tetrachloride^and this blank titrated with thiosulphate to determine

the strength of the bromine solution. The test itself

need be allowed to stand only one or two minutes

before adding 20 to 30 c.c. of 10 per cent solution of

potassium iodide, the .amount necessary depending uponthe excess of bromine present. An excess, of course,

does no harm. In order to prevent any loss of bromine

or hydrobromic acid which would probably occur on

removing the stopper of the bottle, a short piece of

wide rubber tubing, of the sort used for Gooch cru-

1 J. Am. Chem. Soc., XXI, 1084.

42


cibles, is slipped over the lip of the bottle so as to form

a well around the stopper. It is advisable, also, to

cool the bottle by setting it into cracked ice in order to

produce a partial vacuum in the interior. Into the well

formed by the rubber tubing is poured the solution of

potassium iodide and the stopper opened slightly. If

the bottle has been cooled with ice the iodide solution

will be sucked into the bottle, and if it was not cooled

some of the air from the interior of the bottle will

bubble through the iodide solution, being thereby

washed, and allow the iodide solution to enter the

bottle. When sufficient iodide solution has been in-

troduced the bottle is agitated to insure the absorption

of the bromine and hydrobromic acid by the aqueoussolution. The iodine now present is titrated with tenth-

normal sodium thiosulphate, and when the titration is

finished 5 c.c. of a neutral 2 per cent solution of potas-

sium iodate is added. This liberates a quantity of

iodine equivalent to the hydrobromic acid formed, and

on titrating this iodine the bromine substitution figure

may be calculated. The solution of potassium iodate

should be tested for acidity by adding a measured

quantity to a solution of potassium iodide, and if anyiodine is liberated it should be determined jvith thio-

sulphate and a suitable correction introduced into the

calculation. The potassium iodide, the thiosulphate

solution, and the water used should all be tested to see

that they are neutral.

The action between bromine and oil appears to be

practically instantaneous as far as the bromine taken

up by addition is concerned, but it seems likely that

substitution is distinctly affected by the length of time

that the oil and bromine are allowed to remain in

contact.


84. BROMINE VALUES OF VARIOUS OILS.


85. Estimation of rosin in mixtures of linseed oil and

mineral oil. Twitchell's method. A weighed portionof the sample is saponified by boiling with alcoholic

potash, and the alcohol is driven off by prolonged boiling

after diluting with water. The unsaponifiable matter

is shaken out with petroleum ether, as previously de-

scribed under linseed oil, the remaining soap solution

made acid yielding a mixture of fatty and rosin acids.

Heat until the fatty acids have separated on top. Cool,

break the cake of fatty acids with a glass rod, pouringoff the aqueous solution. Treat the acids again with

boiling water, cool, remove to a porcelain dish, and dryat 100 C. until freed from all traces of water.

Two to three grams of the mixed fatty and rosin acids

are weighed off accurately and dissolved in a flask in ten

times their volume of absolute alcohol, and a current of

dry hydrochloric acid gas is passed through for about

forty-five minutes or until the gas ceases to be ab-

sorbed. Allow to stand one hour, then dilute it with

five times its volume of water and boil until clear.

From this point the analysis may be completed volu-

metrically or gravimetrically.

86. Volumetrically. The contents of the flask is

transferred to a separatory funnel and the flask rinsed

out several times with ether. Vigorously shaking, the

acid layer is run off and the remaining ethereal solution

containing the rosin acids washed with water until the

last trace of acid is removed. Fifty c.c. of alcohol are

added, and the solution titrated with standard caustic

potash, using phenolphthalein as an indicator. Therosin acids combine at once with the alkali, whereas

the ethylic esters remain unchanged. The number of

cubic centimeters of normal alkali used multiplied by0.346 will give the amount of rosin in the sample.


87. Gravimetrically. The contents of the flask is

mixed with a little petroleum ether, boiling below 80 C.,

and transferred to a separating funnel, the flask beingwashed out with the same solvent. The petroleumether layer should measure about 50 c.c. After shaking,

the acid solution is run off and the petroleum ether layer

washed once with water, and then treated in the funnel

with a solution of 0.5 gram of potassium hydroxide and5 c.c. of alcohol in 50 c.c. of water. The ethylic esters

dissolved in the petroleum ether will then be found to

float on top, the rosin acids having been extracted bythe dilute alkaline solution to form rosin soap. The

soap solution is then run off, decomposed with hydro-chloric acid, and the separated rosin acids collected as

such, or preferably dissolved in ether and isolated after

evaporating the ether. The residue, dried and weighed,

gives the amount of rosin in the sample.

88. Evaporation test. This test will show very closely

the amount of benzine added along with the drier in the

preparation of boiled linseed oil.

Five grams of the oil to be tested are weighed into

a small flat-bottomed evaporating dish and allowed

to remain undisturbed at a temperature of 100 C.

for three hours. The dish is then removed, cooled

quickly, and immediately weighed. The loss in weight

usually represents the greater portion of mineral oils,

rosin oils, or other volatile matters present in the

sample.

J. Hortvet, state chemist for Minnesota, states that :

"Of fifteen samples represented as raw linseed oil,

when subjected to this test, eleven showed no loss in

weight, while four gave losses amounting to less than

0.3 per cent. Of one hundred and ten samples repre-

sented as boiled oils, sixty gave losses above 2 per cent,


thirty-two showed no loss in weight, and of the remain-

ing eighteen the loss was slight, seldom approaching2 per cent. Forty-seven of the sixty samples which

gave over 2 per cent loss were found to vary in specific

gravity from 0.8835 to 0.9310. All samples not found

adulterated by the usual tests showed a specific gravityof from 0.9310 to 0.9425, with the exception of one

sample which had a specific gravity as low as 0.930,

but by the other tests appeared to be straight raw lin-

seed oil."

89. Hexabromide test.1 The determination should be

made in glass-stoppered weighing bottles about 6 inches

high and 1 inch in diameter, weighing about 30 gramseach. These bottles should be carefully dried and

weighed. Weigh 0.3 gram of oil to be tested, add

25 c.c. of absolute ether, and cool to about C. Addbromine drop by drop until a considerable excess is

shown by the color of the solution. Stir constantly

during the addition, which should be conducted very

slowly, so as to avoid heating. Place tube in ice water

for 30 minutes, then centrifuge for 2 minutes. The bro-

minated oil is thrown to the bottom of the tube. The

supernatant liquid is quickly decanted. Agitate the

precipitate with 10 c.c. ice-cold ether centrifuge and

decant; repeat this procedure twice, thoroughly cooling

the precipitate and ether each time. Finally dry in

steam oven for 30 minutes, cool, and weigh.

90. Linseed oil. The following specifications, recently

adopted by one of the leading railroad companies, are

as comprehensive as any that have come under the

author's observation and may be regarded as typical

of those used by discriminating purchasers of linseed

oil:

1 Proc. Am. Soc. for Test. Mat., Vol. IX, p. 152.


Material.

The material desired under this specification is the

best grade of raw and boiled linseed oil, as shown bythe following requirements:

Raw Linseed Oil.

1. This material must be a good quality of oil of a

pale yellow color, made from No. 1 flaxseed, well clari-

fied by settling and age, and must be unmixed with

any foreign substance whatever.

2. It must not have a greenish color, produced by

unripe or impure seed.

3. Its specific gravity must be between .930 and .937

at 60 F.

4. It must have a flash above 550 F. in an open cuptester.

5. It must contain less than one per cent (1%) of

foots.

6. It must not lose more than one-tenth per cent

(.1%) when heated at 212 F. for three hours.

7. Its saponification value must not be less than 187

or more than 195.

8. Its iodine value (Hiibrs Method) must exceed

170.

9. It must dry without tackiness in less than 75

hours at 60 F. when a layer is spread over a vertical

glass plate in uniform thickness and left in an enclosed

room.

10. It must not contain more than one and one-half

per cent (1.5%) of unsaponifiable matter.

11. Its acid value must not exceed 8.

12. Its specific temperature reaction (Thompson &Ballantyne Method) must not exceed 2.69, water = 1

being taken as the standard.


91. Boiled linseed oil.

1. This material must contain nothing but kettle-

boiled pure linseed oil, and lead, or manganese oxides

or borates, or both, in chemical combination, but not

in suspension.

2. Raw oil mixed with turpentine or benzine dryer,

known as "Bung Boiled" or"Bung-hole Boiled" will

not be accepted.

3. Its specific gravity must be between .937 and .950

at 60 F.

4. It must show between two-tenths per cent (.2%)and five-tenths per cent (.5%) residue after ignition.

5. The salts of lead and manganese must not exceed

four per cent (4%) by weight.

6. The total weight of linseed oil in the boiled oil

must not be less than ninety-six per cent (96%).7. It must not show a flash point below 500 F. in an

open cup tester.

8. It must not contain more than one-half of one

per cent (.5%) of volatile matter when heated at

212 F.

9. It must not contain foots or other suspendedmatter.

10. Its saponification value must exceed 187.

11. Its iodine value (Hubl's Method) must exceed

160.

12. Its acid value must not exceed 12.

13. It must dry without tackiness within 24 hours at

65 to 75 F. when a layer is spread over a vertical

glass plate in uniform thickness and left in an enclosed

room.

14. The unsaponifiable organic matter must not ex-

ceed two per cent (2%).15. It must not contain raw linseed oil, mineral oil,


benzine, turpentine, benzene, rosin, rosin oil, maize or

corn oil, fish oil, cottonseed oil, rape oil, or saponifiable

and unsaponifiable oil, other than boiled linseed oil.

92. Tests. When a shipment is received, a single

sample will be taken from a barrel at random and

the shipment will be accepted or condemned upon the

results of the above test Any standard test, in addi-

tion to those specified above, may be made to ascer-

tain if the shipment meets the intent and requirementsof this specification.

The above specifications require the use of a lino-

leate drier in the preparation of the boiled linseed oil.

The author, however, can see no serious objection to

the use of a properly prepared non-volatile resinate

drier, as the amount that may be used cannot exceed

4 per cent, as stated in section 6.

CHAPTER VII.

ANALYSIS OF THE VOLATILE OILS.

93. Identification. The volatile oil distilled from the

linseed oil, as previously described, may be tested qual-

itatively for spirits of turpentine, stump turpentines,

rosin spirit, petroleum naphtha, and benzole by the

following test :l

Shake in a test tube equal volumes of the turpentineto be tested and concentrated sulphurous acid until

quite thoroughly mixed Set aside, noting the time

of separation and the color of the two strata. Samplesof known purity should be run alongside of the sampleto be tested, and the time of shaking the samplesshould be 'as uniform as possible. Deadwood turpen-

tine, if highly rectified, gives a reaction approachingthat of livewood turpentines.

1. American Turpentine.

Separation takes place very slowly.

Upper Stratum Opaque; milky white.

Lower Stratum Translucent; milky white.

Odor Slight terpene smell.

2. Russian Turpentine.

Quick separation.

Upper Stratum Translucent; faint turbidity.

Lower Stratum Clear and colorless.

Odor Slight pungent smell.

1 Scott's Test for Turpentines, Drugs, Oils and Paints, 1906.

51


3. Deadwood Turpentine.

Medium slow separation.

Upper Stratum Opaque; light buff color.

Lower Stratum Translucent; yellow-amber color.

Odor Distinct tar smell.

4. Livewood Turpentine.

Medium quick separation.

Upper Stratum Translucent; lemon-yellow color.


Odor Mild tar smell.

5. Rosin Spirit.

Medium slow separation.

Upper Stratum Translucent; golden-yellow color.

Lower Stratum Translucent; creamy-white color.

Odor Pungent resin smell.

6. Benzine (Petroleum Naphtha).

Quick separation.

Upper Stratum Clear and colorless.


Odor Sulphurous smell.

7. Benzole.

Quick separation.

Upper Stratum Slight turbidity; faint yellow

color.


Odor Benzole and sulphurous smell.

94. Estimation of petroleum products. If the qualita-

tive test indicates the presence of live or deadwood

turpentine in appreciable quantities, the amount of

ANALYSIS OF THE VOLATILE OILS. 53

petroleum product that may be present is best esti-

mated as follows:

A measured quantity of the volatile oil is allowed to

drop slowly into 300 c.c. of fuming nitric acid con-

tained in a flask provided with a return condenser and

immersed in cold water. A violent reaction takes place

and the flask should be shaken occasionally. When all

action has ceased the contents of the flask is pouredinto a separatory funnel and thoroughly washed with

successive portions of hot water to remove the prod-ucts of the action of the acid on the turpentine. The

remaining petroleum oil is separated and measured or

weighed.

95. Wood turpentine being absent, the amount of

petroleum products may be very closely approximated

by the"Sulphuric Acid Number."

The apparatus and materials required are a large

test tube of considerable diameter, bedded in closely

packed cotton, in a fiber mailing case of suitable size, a

thermometer provided with a platinum flange attached

to the lower end. The lower part of the flange is

bent at right angles to the stem of the thermometer.

A mailing case packed with cotton offers manyadvantages over the regulation asbestos fiber mixed

with plaster of Paris, in that if the test tube is broken

during the estimation the bottom of the mailing case

may be readily removed and the acid-soaked cotton

replaced at once with fresh, while the plaster of Paris

composition has to be washed and dried out, an opera-tion requiring several hours.

96. A neutral mineral oil is required, giving a rise

when treated with sulphuric acid of not more than

3 C.; also a standard bottle of concentrated sulphuric

acid kept for this purpose, and a sample of turpentine


known to be pure. Fifty c.c. of the neutral oil are

pipetted into the large test tube, the temperature noted,

and 20 c.c. of the acid, of the same temperature, added

from the burette in a steady stream, stirring rapidly,

meanwhile, with a uniform motion, to maximum tem-

perature, which is noted. After cleaning and cooling

the apparatus the experiment is repeated exactly as

before, but with the addition of 10 c.c. of pure turpen-tine to the neutral oil. The rise in temperature is

again noted. Similar determinations are made with

mixtures of 50 per cent of turpentine and 50 per cent

of benzine, and also of 75 per cent of turpentine and

25 per cent of benzine. Having thus ascertained stand-

ards for comparison, 10 c.c. of the sample under exam-

ination is carried through in exactly the same manner,the maximum temperature noted, and the per cent of

turpentine and of petroleum product calculated. Com-

mercially pure turpentines will give closely uniform

results. Wood turpentines give lower figures, which

approach those of turpentine the more carefully the

product is prepared and purified. Rosin spirits give a

rise of 7 to 10 C., benzine and benzole 3 to 8 C.

97. Determination of flash point and fire test of petro-

leum products, turpentine, etc. Covered testers. NewYork State Board of Health Tester. This instrument

consists of a copper oil cup holding about 10 ounces

heated in a water bath over a small flame. The cup is

provided with a glass cover holding a thermometer.

This cover also has a hold for the insertion of the test-

ing flame.

The test should be applied as follows: 1

" Remove the oil cup and fill the water bath with

cold water up to the mark on the inside. Replace the

1Report New York State Board of Health, 1882, p. 495.


oil cup and pour in enough oil to fill it to within one-

eighth of an inch of the flange joining the cup and the

vapor chamber above. Care must be taken that the

oil does not flow over the flange. Remove all air

bubbles with a piece of dry paper. Place the glass cover

on the oil cup, and so adjust the thermometer that its

bulb shall be just covered by the oil.

"If an alcohol lamp be employed for heating the

water bath the wick should be carefully trimmed and

adjusted to a small flame. A small Bunsen burner maybe used in place of the lamp. The rate of heatingshould be about two degrees per minute, and in no case

should exceed three degrees.

"As a flash torch, a small gas jet one-quarter of aninch in length should be employed. When gas is not

at hand employ a piece of waxed-linen twine. Theflame in this case, however, should be small.

98. ANALYSIS OF VOLATILE OILS BY THE AUTHOR.

No. 1. Straight petroleum product.No. 2. Wood turpentine.

No. 3. Commercially pure turpentine.

No. 4. Spirits of turpentine, containing about 50 per cent petroleum naphtha.No. 5. Spirits of turpentine, containing about 15 per cent petroleum naphtha.No. 6. Poorly rectified turpentine.

No. 7. Stump turpentine.

No. 8. Straight petroleum product.


99. "When the temperature of the oil in the case

of kerosene has reached 85 F., the testings should

begin. To this end insert the torch into the openingin the cover, passing it in at such an angle as to well

clear the cover, and to a distance about half-way be-

tween the oil and the cover. The motion should be

steady and uniform, rapid, and without any pause.

This should be repeated at every two degrees' rise of

the thermometer, until the thermometer has reached

95 degrees, when the lamp should be removed and the

testings should be made for each degree of temperatureuntil 100 degrees is reached. After this the lamp maybe replaced if necessary, and the testings continued for

each two degrees.

"The appearance of a slight bluish flame shows that

the flashing point has been reached.

"In every case note the temperature of the oil before

introducing the torch. The flame of the torch must

not come in contact with the oil.

"The water bath should be filled with cold water for

each separate test, and the oil from a previous test care-

fully wiped from the oil cup."

100. Open testers. Tagliabue's open tester. This in-

strument is similar to the preceding, except that it is

smaller, the oil cup being of glass and without a cover.

The water bath is filled as before. The oil cup is filled

to within three thirty-seconds of an inch of the top.

The heating flame is regulated to three-fourths of an inch

in height, or to such a height that the temperature of

the oil is raised two and a half degrees per minute until

97 F. is reached, when the test flame is applied and

the testings are made every two degrees until the flash

point is reached.

101. Fire test. The fire test is the temperature at


which an oil will give off vapors which when ignited

will burn continuously. The cover is removed in the

.case of the closed tester, the heating being continued as

described above. The flame may be extinguished bythe use of a piece of asbestos board.

102. Excessive use of volatile oils. An excess of thin-

ners or volatile oils is detrimental to the life of the paint.

Sabin in his work on The Technology of Paint and

Varnish writes as follows :

"Most of the failures of lead and zinc paints are due

to the use of these volatile thinners (turpentine and

benzine). If raw linseed oil is used, it may be desir-

able to add 5 per cent of a good drier. This should be

pale in color, indicating that it has been made at a low

temperature, and should be free from rosin. The latter

is not an easy thing to detect, but if a fair price is paid,

say $1.50 to $2.00 a gallon at retail, and freedom from

rosin is guaranteed by a maker of good reputation, the

buyer ought to feel safe."

103. The presence of a large amount of thinners ren-

ders the paint easier to brush out, and hence the tend-

ency has been to increase the amount of thinners,

especially benzine, because of its low cost, in mixed

paints, resulting in the reducing of the linseed oil to a

percentage below that required to give the proper life

to the paint. The better class of paint manufacturers

seem to consider 4 to 9 per cent of thinners sufficient

for outside house paints.

Excluding the 21 paints containing 12 per cent of

thinners and over, the average amount of thinners in

the remaining 50 paints was 7.3 per cent. The paints

high in thinners were in almost every case inferior

paints, high in inert pigments.

Of seventy-one analyses of white and gray mixed


paints made by the author, the amount of thinners came

between the following limits :

CHAPTER VIII.

TURPENTINE THINNERS.

104. Spirits of Turpentine. This product, which has

long been known to the paint and varnish trade, pos-

sesses several commercial designations, such as "gumturpentine," "oil of turpentine," "turpentine," and

"spirits of turpentine." Its source and distinctive

properties are specifically set forth in the Pharmaco-

poeia of the United States as follows: "Oil of turpen-

tine : A volatile oil distilled from turpentine (a concrete

oleo-resin obtained from Pinus palustris and other spe-

cies of pinus)." "A thin, colorless liquid having a char-

acteristic odor and taste." "Specific gravity 0.855 to

0.870 at 15 C: (59 F.). It boils at 155 to 170 C.

(311 to 338 F.)." The United States Governmentunder the Food and Drugs Act has ruled that a productto be entitled to the above designations "spirits of

turpentine," "turpentine," etc., must comply with

the pharmacopceial requirements above stated, and that

oils obtained by distillation from resinous woods should

be designated "wood" or "stump" turpentine.

105. Adulteration. The paint or varnish manufac-

turer who purchases direct from dealers engaged in the

naval stores business will very rarely receive willfully

adulterated turpentine, but will occasionally receive

shipments of insufficiently refined turpentine contain-

ing various quantities of rosin and resinous matters.

This form of adulteration is easily detected. On the

other hand, the retail dealer and master painter who

purchase from jobbing houses and traveling salesmen59


are very liable to obtain an adulterated article. Recent

investigations have shown that the adulteration of tur-

pentine after it has been shipped from the primarymarkets is a much more common practice than has

been supposed. Usually the adulteration has been ac-

complished with naphtha or other petroleum distillates,

which, owing to their low price, makes this phase of the

industry very profitable. The author believes that the

adulteration of turpentine with rosin spirit or with

wood turpentine is very rare, as the margin of profit is

not large enough to make the proposition sufficiently

attractive.

106. Specifications. The specifications adopted by the

Navy Department Jan. 4, 1908, for spirits of turpen-

tine are as complete as any that have come under the

observation of the author:

1. The turpentine must be the properly prepared dis-

tillate of the resinous exudation of the proper kinds of

live pine or live pitch pine, unmixed with any other

substance; it must be pure, sweet, clear, and white, and

must have characteristic odor.

2. A single drop allowed to fall on white paper must

completely evaporate at a temperature of 70 F. with-

out leaving a stain.

3. The specific gravity must not be less than 0.862

or greater than 0.872 at a temperature of 60 F.

4. When subjected to distillation, not less than 95

per cent of the liquid should pass over between the

temperature of 308 F. and 330 F., and the residue

should show nothing but the heavier ingredients of

pure spirits of turpentine. If at the beginning of the

operation it shows a distillation point lower than 305 F.

this will constitute a cause for rejection.

5. A definite quantity of the turpentine is to be put

TURPENTINE THINNERS. 61

in an open dish to evaporate, and the temperature of

the dish will be maintained at 212 F.; if a residue

greater than 2 per cent of the quantity remains on the

dish it will constitute a cause for rejection.

107. Flash tests. An open tester is to be filled within

one-fourth inch of its rim with the turpentine, which

may be drawn at will from any one can of the lot

offered under the proposal. The tester thus filled will

be floated on water contained in a metal receptacle.

The temperature of the water will be gradually and

steadily raised from its normal temperature of about

60 F. by applying a gas or spirit flame under the re-

ceptacle. The temperature of the water is to be in-

creased at the uniform rate of 2 F. per minute. The

taper should consist of a fine linen or cotton twine

(which burns with a steady flame) unsaturated with anysubstance. When lighted it is to be used at everyincrease of 1 degree temperature, beginning at 100 F.

It is to be drawn horizontally over the surface of the

turpentine and on a level with the rim of the tester.

The temperature will be determined by placing a ther-

mometer, in the turpentine contained in the tester so

that the bulb will be wholly immersed in the liquid.

The turpentine must not flash below 105 F.

1 08. Sulphuric acid test. Into a 30 c.c. tube, gradu-ated to tenths, put 6 c.c. of the spirits of turpentine to

be examined. Hold the tube under the spigot and then

slowly fill it nearly to the top of the graduation with

concentrated oil of vitriol. Allow the whole mass to

become cool and then cork the tube and mix byshaking the tube well, cooling with water during the

operation if necessary. Set the tube vertical and allow

it to stand at the ordinary temperature of the roomnot less than half an hour. The amount of clear layer


above the mass shows whether the material passes test

or not. If more than 6 per cent of the material re-

mains undissolved in the acid this will constitute a

cause for rejection.

109. Adulteration with petroleum products. Adulter-

ation with any considerable quantity of a petroleumdistillate will be indicated by a low specific gravity of

the suspected sample, but if 10 per cent or less be

present the gravity will be lowered only slightly and

distillation through a LeBel-Hennirger column should

be resorted to and the specific gravity and index of

refraction of the different fractions should be deter-

mined as described in the paragraphs devoted to wood

turpentine in this chapter. The rise of temperaturewith sulphuric acid, of the different fractions as de-

scribed in the preceding chapter, will give an approxi-

mation of the amount of petroleum distillate present.

If adulteration with wood turpentine be suspected,

the quantity and character of the heavier fractions

should be carefully determined.

no. Rosin spirit. If rosin spirit is suspected, the test

proposed by Grimaldi may be made use of. Distill

100 c.c. of the oil of turpentine to be examined over a

very small gas flame, and collect the fractions separately

at intervals of 5 degrees of temperature. To the first

five fractions an equal volume of hydrochloric acid is

added, and a few granules of pure tin, and the whole

well shaken and kept in a water bath for five minutes.

The presence of resin spirit (pinolin) is indicated by a

green color, which varies according to the percentageof resin spirit present. Further, one drop of each

fraction is tested by mixing with 2 c.c. of Halphen's

reagent (sulphur dissolved in carbon disulphide) and a

little melted phenol dissolved in carbon tetrachloride.


A trace of bromine vapor is allowed to fall on the

liquid, and in the presence of resin spirit a green color

will develop within half a minute.

in. Wood turpentine. The use of wood turpentineis increasing rapidly. The different products offered

under this heading are of a much more satisfactory na-

ture than those offered for sale a few years ago. This

improvement in quality is due to increased care in refin-

ing, thereby eliminating the objectionable impurities.

As these wood turpentines are offered for sale at a

price of from 2 to 10 cents below that of gum spirits,

it is distinctly to the advantage of the manufacturer of

paints and varnishes to use them, provided he can

secure a well-refined article. Unfortunately, while the

producers of wood turpentine are many, the amount

produced by any one company is comparatively small,

and it is usually impossible for a paint manufacturer

to secure a steady and uniform source of supply. It

therefore devolves upon the paint chemist to examine

a considerable number of wood turpentines yearly, and

to select those best suited for the purpose, or, in other

words, to select those which more nearly resemble the

gum spirits.

112. As is well known, wood turpentine is obtained bytwo methods, viz., by subjecting the stumps or mill

waste to a destructive distillation, whereby the turpen-

tine obtained is contaminated with the decomposition

products from the breaking down of the rosin and the

wood, which renders the refining of the turpentine a

very difficult matter. In fact, a paint manufacturer

will usually discriminate against a turpentine obtained

by destructive distillation. The other process of ob-

taining wood turpentine is by steaming the chipped

stumps or mill waste, thereby avoiding any serious


decomposition of the wood or rosin contained in it.

On redistillation a turpentine product is obtained which

has a pleasant odor, suggestive of pine wood, and which

will distill largely within the accepted limits of the ordi-

nary gum spirits, but which will contain a varyingfraction of the heavier pine oils.

113. A suitably selected" Steam" turpentine is fully

the equal of the gum spirits for mixed paints and for

medium or slow-drying varnishes. For such quick

drying varnishes as it is desirable to prepare with the

aid of turpentine alone or with naphtha, a mixture of

40 per cent of gum spirits with 60 per cent of a steam

wood turpentine is as desirable as the gum spirits

alone.

. 114. Valuation of wood turpentine. The valuation of

a wood turpentine aside from its odor will depend

largely upon its distillation figures and the specific

gravities of the fractions obtained. The more usual

method of distilling with the aid of direct heat in a

side-necked distilling flask is open to serious objection

for two reasons: first, the portions that condense in

the neck of the flask and drop down on the hot liquid

below will cause a certain amount of"cracking" or

decomposition, coloring the undistilled residue yellow;

second, when only a small amount remains in the dis-

tilling flask the vapors become superheated, which

may indicate a distilling temperature several degrees

above the normal figure. Under the same conditions

pure water can be made to indicate a distilling tempera-ture of as high as 107 C., due to the superheating of

the aqueous vapor.

115. Distillation with steam. The most satisfactory

method of conducting the distillation is to use steam,

and thus avoid direct heating altogether. By the use


of a LeBel-Henninger 5-bulb distilling tube or column

the heavier fractions in the turpentine can readily be

separated and their gravities examined, and the non-

volatile residue can be examined as to color and per-

centage.

1 1 6. Author's modification. Three hundred cubic cen-

timeters of the sample to be examined are placed in

a 500 c.c. Erlenmeyer flask provided with a 5-bulb

LeBel-Henninger column and with a steam supply tube

extending nearly to the bottom of the flask. The con-

tents of the flask are raised by direct heat to about

80 or 90 C. The source of heat is then removed and

live steam admitted, the distillate being collected in a

100 c.c. graduated cylinder, which is changed as soon

as the 100 c.c. mark is reached. This operation is

continued until all the volatile portions have distilled

over, and the number of cubic centimeters of turpen-

tine and of water in each 100 c.c. cylinder is then

noted.

117. Law governing distillation of mutually insoluble

liquids. In the distillation of a mixture of two mutu-

ally insoluble liquids, each of which has a definite boil-

"ing point, it is a well-known fact that the mixture will

distill at a constant temperature, in the ratio of the

products of their respective vapor densities and vapor

tensions, at the temperature of distillation. In the

above case, when we have a mixture of water and gumturpentine, the ratio of distillation is approximately 60

parts of turpentine to 40 parts of water, the distilling

temperature being about 94 C. This ratio holds only

for that portion of the turpentine which distills with

direct heat between 156 C. and 160 C. The heavier

fractions require a much larger volume of water for

their distillation.


118. Distillation figures of a gum turpentine. The fol-

lowing table illustrates the distillation results obtained

with a gum turpentine slightly below average:

119. Distillation figures of a wood turpentine. A wood

turpentine under similar treatment gave the following

results:

Fraction No. 8 was of a straw color and Nos. 9 and

10 were yellow. This particular sample represented a

rather high grade of a destructively distilled wood

turpentine.

120. In order to conduct the distillation successfully

and rapidly the apparatus required should always be

kept set up ready for use. The specific gravities can


readily be determined with a Westphal balance, and it

will be found that the entire operation can be con-

ducted in the same length of time as is required for

the more ordinary distillation. This method thor-

oughly differentiates the heavier fractions and leaves

the residue uncontaminated with decomposition prod-

ucts such as are obtained when direct heat is applied.

It is of course understood that the distillations should

always be conducted under uniform conditions.

121. Detection of petroleum products. If there is anyreason to suspect adulteration with petroleum products,

such as benzine, petroleum spirits, or kerosene, the de-

termination of the index of refraction of the different

fractions and the rise of temperature with sulphuric

acid will reveal even a very small percentage of adul-

teration.

122. Geer's modification. In cases of controversy or

in court procedure, the modification worked out byGeer (U. S. Dept. of Agriculture, Forest Service, Circu-

lar 152), which is somewhat similar to the author's

method, may be followed to advantage, as it is moreelaborate and specific in its details. For ordinary com-mercial usage, however, it is somewhat lengthy andtedious in its application.

123. Standards of purity. It is well-nigh impossibleto establish standards with regard to the amount of

non-volatile matter permissible in a high-grade gumturpentine or of a heavy turpentine and non-volatile

matter permissible in wood turpentine. The author has

rejected numerous samples of gum turpentine contain-

ing non-volatile matters in excess of 1.8 per cent, as the

non-volatile matter was of a distinctly resinous nature.

In a wood turpentine the non-volatile matter should

not exceed 2 per cent, nor contain more than 10 per


cent of a fractionated portion with specific gravity

above 0.872. Usually each paint chemist will estab-

lish his own standards, based on his own experience.

He should, however, keep for future reference a pint

sample of each distinctive turpentine examined. These

should be kept in a tightly closed can or in a bottle

which has received a heavy coating of black paint in

order to avoid the chemical changes caused by light.

A variety of such samples, together with the data apper-

taining to them, color, odor, flash point, gravity, and

distillation figures, including the specific gravities of the

fractions and their indices of refraction, will enable the

chemist to pass on, or place a comparative valuation on,

any given sample rapidly and accurately.

124. The heavier turpentines. In the production of

wood turpentine by steaming or by extraction a series

of heavier terpene bodies are obtained. In some

instances these are allowed to remain in the turpen-

tine, and of course are readily detected and estimated

by the fractionating method above described. Gen-

erally these terpenes are removed to a certain extent

by the producer and placed on the market under some

such name as pine oil. Like the wood turpentines

found on the market several years ago, they differ

greatly in value and desirability, no uniform standard

having been established. The more desirable varieties

have a mild, pleasant, fragrant pine odor, somewhat

suggestive of camphor, and a specific gravity varying

between 0.890 and 0.925. The heavier varieties, 0.925

to 0.940, are not so desirable for paint or varnish pur-

poses, owing to their less pleasant odor and compara-

tively slight volatility.

125. Correct designation. The name "pine oil" as

applied to these terpenes is, in the opinion of the author,


somewhat of a misnomer, and a name like"heavy tur-

pentine"

is much more applicable, as these bodies

very closely resemble the ordinary turpentine in their

properties and show little analogy to the fixed or non-

volatile oils, or to the rosin oil, except those fractions

having a gravity of upwards of 0.940.

126. Properties. A desirable"heavy turpentine" is

completely volatile, without leaving an oily stain, in

about 6 hours, when 3 drops are allowed to fall on the

same spot on a sheet of ordinary filter paper. Whenused with linseed oil such a turpentine acts as a true

drier, and in this respect is even superior to ordinary

turpentine. As its rate of evaporation from the oil or

paint film is much slower, its effect is exerted for a

much greater length of time. This can readily be

demonstrated by placing on a sheet of glass some raw

linseed oil, a mixture of 90 parts of linseed oil to 10 of

turpentine, and 90 parts of linseed oil to 10 of heavy

turpentine; then placing the sheet of glass at an angle

of about 30 degrees from the perpendicular and

noting the rate of drying. For ready mixed paints

for outside use and for liquid driers for the store and

manufacturing trades, the heavy turpentines offer great

possibilities, as these turpentines can be obtained for

from 10 to 15 cents below gum turpentine, and by reason

of their great drying strength permit the use of con-

siderable quantities of naphtha for thinning to suitable

consistency.

127. Value as a drier. It is quite generally conceded

that one of the causes of the ultimate breaking downof linseed-oil paints is the fact that the metallic driers

used to hasten the drying of the linseed oil do not

cease their action on accomplishing the drying of the

paint film, but continue their oxidizing action, slowly


but nevertheless surely, converting the dry but elastic

oil film, or linoxyn, into a brittle, non-elastic substance,

which, having lost its life or binding strength, readily

crumbles and disintegrates. The greater the extent to

which metallic driers can be avoided and yet secure

proper drying of the paint, the longer the life of the

paint. A drier composed of naphtha, heavy turpen-

tine, and a small quantity of resinate or linoleate drier

affords a product much superior to the medium or low-

priced driers on the market. The same reasons hold

good for the use of the heavy turpentines in outside

mixed paints.

128. Use in varnishes. In quick-drying varnish prod-ucts and paints the use of a drier is not advantageous

except in special cases. It is possible to make extremelyshort oil varnishes, 6 to 7 gallons of oil per 100 Ibs. of

gum, by starting the thinning at 450 F. to 480 F. with

a heavy turpentine of specific gravity of about 0.910,

using about 2 gallons or just a sufficient amount to

reduce the temperature of the kettle to the point of

safety for the addition of turpentine or petroleum

spirits for the completion of the thinning. If added

promptly it will save a kettle of varnish that has begunto curdle in the initial stage of thinning from lack of

sufficient heat or other causes.

129. Standard of purity. As before stated, the heavyturpentines should be selected with regard to freedom

from material percentages of fractions heavier than 0.930.

Also, as some of the largest producers of these oils obtain

their products with the aid of a petroleum solvent, the

presence of mineral oils must be looked for, which if

present in quantity will leave a greasy stain on paper.

As the boiling point of a heavy turpentine will be be-

tween 190 C. and 225 C., distillation with direct heat


will cause a certain amount of decomposition, especially

of the heavier fractions, and distillation at 100 C. with

steam through a LeBel-Henninger column results in a

very slow distillation, about 15 c.c. of turpentine to

85 c.c. of water. It will be found advisable to heat the

distilling flask in a paraffine oil bath to 160 C., and

while maintaining this temperature with care, pass a

current of steam through the heated turpentine, dis-

till, and examine the fractions as above outlined with

special reference to the index of refraction.

Polymerization with sulphuric acid does not yield

satisfactory results, as a considerable percentage re-

mains unacted upon.

CHAPTER IX.

A word maybe said in i *!?* ^m with, the increased use of volatile

products as paint thinness* In discussing

theprob-

or in part the luiprntiatl

of turpentine substitutes,

the exact function erf the

to prepare an

prapevtaatune be free from objectionable char-

to the views

of the

73

to produce a "flat" or "semi-flat" surface,

ance, as in the ease of paints intended for inside we;to lender the paint more fluid without the use of an

-..._,..-. 4- *jt ,.t| j - *IL , , . . . _; . : ~\ ~

excessve amount ot 0115 10 increase tne afifgu 01 tncJ ? ' " * M- 9 jJ- ^^^^M^^nfSfl^M A^M! l^w^^vm*CvMarymgot tne pamt Dotn DyevaporaooiianciDy onuixa-

ikm; and finally, to act as a Heading a0ort om the4the pant whiter; this, hipi.m, is not so

urtnin their

jipiuiluil aliili ilmii mii

letnn distillales with which the

amiB*

H is dedred, Le., whether of Texas, Ruffian, or of

some other origin. It is prepared so thai it has a flask

point rfgjitly above that of turpentine, and hence as a

fire rist it is as safe as iifi^pniMn&j wiMen is in

and at a rate about or slightly

turpentine. In seeming penetration of the paint it is

fuUy equal to turpentine and is free front objectionable

piliim In uulei to oviscome the drfi<jmcy off not

g the paint in drying by oikiiation and tne

lack of blesuAing acdoa on the Enseed ofl, several paint

pM^if^.ijMMM. add a Bbiiiil percentage off spirits of

turpentine to

153. Reporting

ahras of paints should be very careful in

composition of the volatile oik used in


should not confound these turpentine substitutes with

ordinary benzine, which costs considerably less than

half as much and is dangerous to use on account of the

fire risk and is too volatile to be accepted as a proper

turpentine substitute. The analysis of these substitutes

when once incorporated into the paint is somewhat

difficult, but with care may be obtained by distillation,

as above mentioned. Having secured the volatile dis-

tillate and having freed it from all traces of water, it

may be redistilled, using a small distilling flask and

carefully noting the temperatures at which the product

passes over. The substitutes of recognized merit dis-

till usually between 150 and 200 C. Any benzine

present will pass over below 150 C., and kerosene

mostly above 200 C. If the latter is present, how-

ever, a large portion will not be volatile in the steam

distillation and will remain in the linseed oil, being

readily detected in the latter by pouring six drops in a

few cubic centimeters of an alcoholic solution of potash,

boiling gently for two minutes, and pouring into a little

distilled water, a decided cloudiness indicating the pres-

ence of unsaponifiable petroleum oils.

134. Analyses. The following data clearly indicate

the characteristics of the petroleum products which are

now being offered in large quantities as satisfactory

in whole or in part for spirits of turpentine :

TURPENTINE SUBSTITUTES. 75

ANALYSIS OF DIAMOND T SPIRITS.

Specific Gravity, 0.8185 - 41.38 Beaume.

Flash Test, 96 F. (open)- 35.56 C.

DISTILLATION BY TEMPERATURES.C. C.

Commencing at . ...'.-.'

'. . . . . 151.67

From . . , , . . 151. 67 to 157.23

Do. . . . . . . . ...... 157.23 to 162.78

Do 162.78 to 168.34

Do 168. 34 to 173. 89

Do 173.89 to 179.45

Do 179. 45 to 185. 00

Do 185.00 to 190.56

Do 190. 56 to 196.11

Do. ,^.' V . 196.11 to 201. 67

Do 201. 67 to 207. 23

Do 207.23 to 212.78

Do . 212. 78 to 218. 34

Do , \ . . . 218.34 to 223.89

Do 223.89 to 229.45

Do 229.45 to 235. 00

Do 235.00 to 240. 56

Do 240.56 to 246.11

Do. ... 246.11 to 248. 89

10%17%28%38%47%56%65%71%76%80%85%88%91%93%94%95%97%


DISTILLATION FIGURES OF TEXENE, TURPENTINE, ANDNAPHTHA.

135. Distillation with steam through a LeBel-Hennin-

ger column, as described in the preceding chapter, with

the Sun Oil Company's No. 18 Oil, which is a well-

known petroleum substitute, gave the following results :

PETROLEUM SPIRITS.

Flash Point, 92 F. (Open). Distillation, 145 C. - 225 C.

Time Distillation, P.S., 74 m. 304 c.c.

Residue .8

CHAPTER X.

THE INERT PIGMENTS.

136. Classification. The inert pigments comprise

Barium sulphate (barytes, blanc fixe).

Barium carbonate.

Calcium carbonate (whiting, Paris white, white

mineral primer).

Calcium sulphate (gypsum, terra alba).

China clay (kaolin).

Asbestine (magnesium silicate) .

Silica (silex).

The properties of the various active pigments have

been discussed under their methods of manufacture andneed not be taken up here.

137. Inert pigments. The inert pigments have widelydifferent properties, not only from a chemical stand-

point but from a physical standpoint as well; and while

two pigments may have the same chemical composition,

they may differ greatly in physical properties, produc-

ing entirely different results when used in paints.

Hence it is practically impossible from the chemical

analysis to judge the service values of paints containing

inert pigments. Chemical analysis, however, in con-

junction with a careful microscopic examination, espe-

cially if a polarizing microscope be used, may give

some idea of what the service value should be.

138. Barium sulphate (barytes, blanc fixe). Barytes is

perhaps the most extensively used of the inert pigments.It more nearly approximates white lead in specific grav-

77


ity and oil-taking capacity than any of the others. It

is absolutely unaffected by acids, alkalies, or atmos-

pheric influences of any kind. Its hiding power or

opacity when ground in oil is very low, and hence whenused in any considerable percentage in a mixed paint

or combination lead its presence is indicated by the

reduced opacity of the paint film. The requisites

of a high grade of barytes are whiteness and fineness.

Commercial grades often contain varying percentages

of calcium carbonate, which will be indicated by effer-

vescence when treated with hydrochloric acid. Occa-

sionally a considerable percentage of calcium sulphate

may be found which may be readily estimated by

extracting with boiling water and determining the

calcium in the filtrate.

During the past few years numerous new barytes

deposits have been opened up and in some instances

have afforded a product of doubtful value to the paint

manufacturer, due to a lack of proper grinding and a

peculiar crystalline structure which gives much trouble

in the paint mixer and grinding mill and causes excessive

settling in the package. In fact it is always advisable

for the chemist to have his report confirmed by trying

out the product in question in one or more regular

formulas in the factory. Neither is the color maker

immune from trouble with his barytes, especially in the

manufacture of chrome greens, resulting in excessive

settling of his green in mixed paints and manufacturingtrades paints, especially dipping paints. The cheaper

grades of barytes have a yellowish gray color and are

often treated with sulphuric acid to improve the color

by removing the iron. A considerable portion of the

barytes on the market is"blued,'

7

either by precipitat-

ing as Prussian blue, the iron sulphate obtained by

THE INERT PIGMENTS. 79

the treatment with sulphuric acid or by adding the

Prussian or ultramarine blue separately. The major-

ity of paint manufacturers, however, prefer to blue

their goods themselves, if necessary, during the pro-

cess of manufacture. The fineness with which baryteshas been ground can easily be determined by examina-

tion under the microscope after the acid soluble pig-

ments have been dissolved out.

139. Free acid. Each shipment of barytes should be

carefully examined for free acid, which can be easily

done by placing a sample on a strip of litmus paper in

a watch glass and moistening with a little distilled

water. The degree of reddening will indicate whether

more than a minute trace of free acid is present. In

case of doubt, a quantitative determination should be

made. The presence of free sulphuric acid, especially

in the case of a combination lead ground in a warm

mill, will cause a decided hardening in the keg. Also

if an acid barytes be ground with lithopone the offen-

sive odor of hydrogen sulphide will be very apparent,

not only in the grinding room but when the packageis subsequently opened.

140. Blanc fixe. This pigment is a precipitated barium

sulphate. Owing to its more amorphous character it

has a much greater hiding power than barytes. Its

oil-taking capacity is greater; it does not settle in a

paint so badly as barytes and is much whiter; its cost,

however, is about twice as great. It is largely used as

an inert base for organic lakes.

141. Barium carbonate. This pigment is used compar-

atively little in the United States as a paint pigment.In physical and chemical properties it much resembles

white mineral primer, a form of calcium carbonate,

although it does not require so much oil in grinding.


Its specific gravity is about that of barytes. It dis-

solves readily in acetic, nitric, and hydrochloric acids;

sulphuric acid converts it slowly into insoluble barium

sulphate. In the hundreds of mixed paints examined

by the writer barium carbonate was found to be present

in only one paint, although its presence in certain

organic lakes, especially in certain shades of red, is not

uncommon in a precipitated form.

142. Calcium carbonate, Paris white, whiting, alba whit-

ing, white mineral primer.

Under the heading of calcium carbonate we have

three distinct classes of pigments, those obtained

from

(1) English cliffstone or similar chalk formations,

such as Paris white, gilders' whiting, and commercial

whiting.

(2) Marble or a crystalline calcium carbonate, such

as marble dust, white mineral primer, etc.

(3) Precipitated calcium carbonate, such as alba

whiting.

The English cliffstone pigments are usually put on

the market in about three grades. The first grade is

the whitest and most finely ground and bolted and is

usually sold under some such name as Paris white, and

finds its use largely in first-quality mixed paints and

combination leads. The second grade is coarser

and has a slightly grayish tint and is usually sold

under some such name as gilders' whiting. It is also

bolted, and is used in second and third grade paints.

The third grade is inferior in color and fineness to the

other two grades. It finds its chief use in kalso-

mine; although it is used in some of the very inferior

paints, it never should be, owing to the fact that it


is not bolted, and therefore contains some relatively

large particles. It is usually sold as commercial

whiting.

143. White mineral primer. The various forms of

white mineral primer are of an entirely different nature

physically from the cliffstone products, being fragmentsof small crystals. They have very little body in oil,

being nearly transparent. They are usually whiter

than Paris white and possess much greater tooth, but

are not much used in mixed paints owing to the fact

that they settle badly in the can and have very little

opacity. They find their chief use in primers and in

putty for making it work shorter. Being of a crystal-

line nature it is natural that they require less oil in

grinding than Paris white.

Alba whiting and other precipitated calcium car-

bonate pigments are very white, but being very light

and fluffy require an enormous amount of oil in

grinding.

While it is not an easy matter to distinguish these

different products in a paint, yet the microscope is of

much value in determining the fineness of grinding.

The paint chemist is frequently required to pass on

samples of Paris white, which appear much whiter

than his standard samples. On close examination these

will usually be found to possess a semicrystalline nature,

therefore are deficient in opacity, and are not true

Paris whites.


Quantitative Analysis of the Calcium Carbonate

Pigment.

144. Moisture. Heat 2 grams at 105 C. for two hours,

cool, and weigh.

145. Silica. Weigh one-half gram into a suitable sized

casserole. Cover, add 5 c.c. of hydrochloric acid (sp.

gr. 1.1) by means of a pipette, without raising the cover.

After the effervescence has ceased, rinse off the beaker

cover with a little hot water. Evaporate to dryness

and cool. Add 2 c.c. of concentrated hydrochloric

acid, again evaporate, and heat gently for a few min-

utes. Cool and dissolve in 100 c.c. of hot water and

10 c.c. of strong hydrochloric acid, filter, wash, ignite,

and weigh. If 1 per cent or under, it may be regardedas silica. If more, it should be fused with sodium car-

bonate, dissolved in water and hydrochloric acid, in

the same casserole, and evaporated to dryness. Heat

gently. Add a little more hydrochloric acid and de-

hydrate again. Finally take up in water acidulated

with hydrochloric acid, filter, ignite, and weigh as silica.

The filtrate from the silica fusion is treated as described

under 149.

146. Alumina and iron. The filtrate from the original

residue is made just perceptibly alkaline with dilute

ammonia, the iron and alumina filtered off, ignited, and

weighed in the usual manner.

147. Calcium. The filtrate from the iron and alumina

is made acidwith acetic acid, boiled, and 40 c.c. to 50 c.c.

of ammonium oxalate solution added. Continue boil-

ing for 5 minutes, filter, and wash thoroughly. Return

filter and precipitate to same beaker. Add 200 c.c. of

boiling water and 25 c.c. of dilute sulphuric acid and


titrate with standard tenth-normal potassium perman-ganate.

1 c.c. tenth-normal permanganate = 0.0028 g. CaO1 c.c. tenth-normal permanganate = 0.0050 g. CaCOs1 c.c. tenth-normal permanganate = 0.0086 g. CaSO4 . 2H2O1 c.c. tenth-normal permanganate = 0.0068 g. CaSC>4

1 c.c. tenth-normal oxalic acid = 0.0028 CaOCryst. oxalic acid X 0.444 = CaO

EXAMPLE: Wt. sample taken = 0.250 g.

Titration with permanganate = 50.5 c.c.

25 c.c. standard iron solution =31.8 c.c. permanganate1 c.c. standard iron solution = .007 g. iron

1 c.c. tenth-normal iron solution = .0056 g. iron

25 c.c. standard iron solution = 31.25 c.c. tenth-normal per-

manganate.1 c.c. permanganate solution used = 0.983 c.c. tenth-normal per-

manganate.50.5 c.c. X 0.983 = 4964 c.c.

(49.64 c.c. X 0.0050) ^ 0.250 = 99.28% CaCO3 .

148. Magnesium. The filtrate from the calcium oxa-

late is cooled and treated with hydrogen sodium phos-

phate, allowed to stand for one-half hour, then 25 c.c.

of strong ammonia added, allowed to stand one hour, fil-

tered on a Gooch crucible, ignited, and weighed.Wt. precipitate = 0.7575 = Wt, Magnesium car-

bonate.

149. Calcium and magnesium oxides. The filtrate from

the silica fusion should be treated separately from the

main filtrate, as the calcium and magnesium obtained

from it are to be reported as oxides and not as carbon-

ates. Precipitate the iron and alumina, calcium and

magnesium, as described under 146, 147, and 148.

NOTE. If the sample contains considerable magnesium carbonate,

the following modification should be observed. After filtering off the

iron and aluminium hydroxides, they are redissolved in another beaker,

diluted, and again precipitated and filtered into the main filtrate. The


same treatment is given to the calcium oxalate. Magnesium com-

pounds when present in considerable percentages badly contaminate the

other precipitates.

150. ANALYSES OF CALCIUM AND MAGNESIUM CARBON-ATE PIGMENTS BY AUTHOR.

Undetermined 0.10 0.21 0.05 0.13

100.00 100.00 100.00 100.00

151. Calcium sulphate (gypsum, terra alba). This pig-

ment is found in combination white leads and exterior

white paints only to a limited extent. Its chief use

seems to be in certain lines of railroad paints and in

dipping or implement paints. It is also used to some

extent as a base upon which to strike certain organic

lakes, notably the para reds. The writer, despite the

favorable opinions of many eminent paint authorities,

does not believe that calcium sulphate, or gypsum, as

it is more commonly known, is adapted for use in

exterior paints owing to its solubility in water, it being

soluble about one part in five hundred. A linseed oil

paint film is by no means impervious to moisture, and

the continued action of rains and storms cannot be

otherwise than favorable, as the solvent action of the

water in removing a portion of the gypsum renders the

paint film more porous and its disintegration more

rapid.

152. Calcium sulphate in oxide of iron pigments. Ve-

netian reds often contain 50 to 80 per cent of cal-

cium sulphate. The better class of Venetian reds are


composed of 50 per cent of ferric oxide and 50 per cent

of calcium sulphate. This calcium sulphate should

not be confounded with the forms above discussed,

as it has been subjected to the action of a high heat

and is therefore insoluble in water, and is regarded as

a proper constituent of Venetian reds.

153. Analysis of agalite, terra alba, etc. These pig-

ments have essentially the same composition calcium

sulphate plus 2 molecules of water. The same method

of analysis may be pursued as described under the

analysis of calcium carbonate pigments. In addition,

it is necessary to determine the combined water byignition to constant weight, and also to determine the

combined sulphuric acid, which may be done as fol-

lows:

Boil 0.5 gram of the pigment in 30 c.c. of strong

hydrochloric acid for 10 minutes in a covered beaker.

Dilute with 250 c.c. of boiling water, boil 5 minutes,

filter, make filtrate neutral with ammonia, then dis-

tinctly acid with hydrochloric acid, and bring to boiling.

Add 25 c.c. of barium chloride, boil 10 minutes, filter,

wash with hot water, ignite, and weigh.

Wt. barium sulphate X 0.3433 = combined sulphuricacid.

154. ANALYSES OF CALCIUM SULPHATE PIGMENTS BYAUTHOR.

I. II.

Agalite. Terra Alba.

Moisture and combined water ... 19.02 20.67Iron oxide and alumina 0.29 0.67Silica 5.60 0.70Calcium sulphate 74.90 76.52Magnesium sulphate 1 . 36Undetermined 0.19 .08

100.00 100.00


155. Aluminum silicate (China clay, kaolin, tolanite).

This pigment also finds but little use in combination

white leads, owing to its low specific gravity. It is,

however, used extensively in mixed paints, implement

paints, and as an inert base upon which to strike paraand other organic reds, especially for colors which are

used in dipping paints. Its functions and properties

are very similar to those of magnesium silicate, it being

essentially a suspender for preventing settling in paints.

It is very inert in its action with acids and alkalies.

Strong hydrochloric acid with continued boiling will

dissolve a very slight fraction of 1 per cent, hence

traces of aluminum may be found in a hydrochloric

acid solution of a paint containing aluminum silicate.

Some of the silicates much in favor with the paint trade

contain a considerable percentage of what is apparentlyuncombined silica. In mixed paint it is often used

with magnesium silicate. Hence a microscopic exam-

ination is usually required to determine whether the

latter is present or not. It yields to treatment byfusion with sodium carbonate more readily than mag-nesium silicate. When subjected to a high tempera-ture it loses 11 to 13 per cent of water of hydration.

156. Magnesium silicate (asbestine pulp, talcose).

This pigment is sold under the various names of white

silicate, asbestine, asbestine pulp, etc. Large amountsare obtained from natural deposits in and around

Gouverneur, N. Y. It has a very low specific gravity,

and is much used in lead and zinc paints to preventthose pigments from settling hard in the bottom of the

package. Chemically it is very inert, being unacted

upon by any of the ordinary acids. It is, however,

decomposable with hydrofluoric acid in a platinum dish


and by fusion with sodium carbonate. Fusion with

potassium bisulphate decomposes it only partially.

Continued heating at a bright red heat will cause a

loss of 3 to 5 per cent in weight, due to loss of water

of hydration. It is easily recognized under the micro-

scope by the fibrous or rod-like structure of the

particles.

157. Silica (silex). There are two distinct kinds of

silica to be found on the market, that obtained from

crushed quartz, which is a very pure form of silica, and

an impure form found in natural deposits, especially in

Illinois. The former possesses a very pronounced"tooth," under the microscope the particles are very

sharp and jagged, and it is quite transparent in oil.

The second form is composed of rounded particles of a

complex chemical nature; besides free silica there are

usually found associated with it calcium carbonate,

aluminum silicate, and magnesium silicate, besides a

small amount of magnesium carbonate. This product

requires more oil in grinding, and has much more body,but considerably less tooth.

158. Fusion with sodium carbonate. One-half gram is

thoroughly mixed with 10 grams sodium carbonate and

one-half gram potassium nitrate placed in a covered

platinum crucible and fused until quite clear and quiet.

Cool, and dissolve in water in a casserole, provided with

beaker cover, on the hot plate. Make acid with hydro-chloric acid, adding the acid with a pipette, keepingthe casserole covered to avoid loss. Also rinse out the

crucible with a little acid. After the effervescence is

over, wash off the watch glass, and evaporate to dryness

on the sand bath. Cool, moisten residue with hydro-chloric acid, and evaporate to complete dryness again.

Dissolve in 10 c.c. of hot water and 10 c.c. of hydro-


chloric acid. Filter, ignite, and weigh precipitate as

silica.

If barytes is suspected to be present, the sodium car-

bonate fusion is dissolved in hot water and the barium

carbonate filtered off, dissolved in hydrochloric acid, and

precipitated with a few drops of sulphuric acid in the

usual manner. The filtrate from the barium sulphate

is added cautiously to the filtrate from the barium

carbonate, the mixed filtrate made acid, and the silica

dehydrated as described above.

159. The filtrate from the silica is made slightly alka-

line with ammonia and the iron and alumina precipi-

tated, washed, redissolved, reprecipitated to free from

sodium salts, filtered, ignited, and weighed in the usual

manner.

The filtrate from the iron and alumina is treated with

ammonium oxalate and after allowing to stand in a

warm place the calcium is filtered off, ignited, and

weighed as calcium oxide. If desired the calcium

may be estimated volumetrically, as described under

the analysis of white mineral primers, etc.

The filtrate from the calcium is tested for magnesiumwith sodium hydrogen phosphate, and if found, esti-

mated in the usual manner.

The carbon dioxide is determined in a separate por-tion of the sample. The amount found is combined

with the requisite amount of calcium to form calcium

carbonate. Any excess of calcium is reported as the

oxide, it being in combination with the silica. The

magnesium is usually calculated as magnesium oxide,

unless the carbon dioxide is in excess of the calcium

present, in which case it is calculated to magnesiumcarbonate and the remainder of the magnesium to the

oxide.


160. Moisture. Heat 2 grams at 105 C. for 3 hours,

cool, and weigh.

161. Combined water. Weigh 2 grams into a platinum

crucible, heat in the muffle or over a strong Bunsen flame

for 1 hour. Loss in weight equals combined water un-

less an appreciable amount of carbonate is present.

162. Determination of the alkali metals, sodium and

potassium. Heat gently 1 gram of the sample inti-

mately mixed with 1 part ammonium chloride to 8 parts

of pure calcium carbonate. The alkalies as well as

some of the calcium are converted into chlorides. Cool,

treat with water. The alkali chlorides will dissolve,

while most of the calcium remains undissolved. Filter,

precipitate the calcium with ammonia and ammonium

carbonate, filter, evaporate to small bulk, and precipi-

tate any remaining calcium. Filter. The solution nowcontains as fixed compounds only sodium and potas-

sium chlorides. Evaporate nearly to dryness in a

weighed platinum dish on water bath. Cover and dry

completely on the hot plate, exercising great care to

prevent the spattering of the material. Finally heat

gently with a Bunsen burner, which must be held in the

hand and the flame waved under the dish and removedas soon as any portion of the dish becomes red hot.

Cool and weigh. Take up in water and add an excess

of platino-chloride solution. Evaporate to a sirupy con-

sistency, take up with 80 per cent alcohol, filter througha weighed Gooch crucible, and wash with alcohol. Dryin the steam oven.

Wt. of precipitate X 0.1941 = wt. Potassium oxide.

Calculate to potassium chloride, subtract from the

weight of the mixed chlorides, thus obtaining the weightof sodium chloride, which may then be calculated to

sodium oxide.


163. ANALYSES OF SILICAS BY AUTHOR.I. II. III.

Moisture 0.21 0.06 0.43Ferric oxide and alumina ... 0.28 0.01 1.48Silica 99.40 99.88 53.48Calcium carbonate 26 . 12

Magnesium carbonate 18. 17Undetermined 0.11 0.05 0.32

100.00 100.00 100.00

ANALYSES OF MAGNESIUM SILICATES BY AUTHOR.I. n.

Moisture 0.50 0.29Combined water 2 . 99 3 . 44Silica 58.60 56.76Ferric oxide . 09 . 18Alumina 1.43 2.84Calcium carbonate 2 . 77Calcium oxide 5 . 63

Magnesium oxide 30 . 45 33 . 50Undetermined 0.31 0.22

100.00 100.00

ANALYSES OF TOLANITE BY AUTHOR.Moisture . 22Combined water . 10.42Ferric oxide 0.09Alumina sol. in HC1 . 39Silica 65.51Alumina 23.12Undetermined 0.25

100.00

TYPICAL ANALYSES OF CLAYS.1

I. n. in. IV.

Silica 45.45 66.20 72.66 64.84Alumina 38.75 24.11 17.33 24.31Ferric oxide 1.15 0.79 1.05 1.60Calcium oxide 0. 13 0. 11

Magnesium oxide 0.11Potassium oxide . 17 . 96 . 36 . 24Sodium oxide . 38 . 32Combined water, etc 13.05 7.20 8.09 8.58Undetermined 1.32 0.74

100.00 100.00 100.00

1Geological Survey of North Dakota, 1901.

100.00


164. Specifications for paste wood filler. ("Bureau of

Supplies and Accounts, Navy Department," 1902.)

Paste wood filler shall contain the following:Per cent.

Silicate 65

Raw linseed oil 10

Best quality rubbing varnish 25

The silicate must be dry, finely ground, and when

subjected to microscopic test the particles must show a

needle-pointed shape. Powdered silicate which shows

spherical fragments will not be accepted.

The raw linseed oil must be absolutely pure, well-

settled oil, of the best quality; must be perfectly clear,

and not show a loss of over 2 per cent when heated to

212 F. or show any deposit of foots after being heated

to that temperature. The specific gravity must be

between 0.932 and 0.957 at 60 F.

The rubbing varnish to be of the best quality and

to be equal in quality to the standards of rubbing var-

nish, which can be seen on application to the general

storekeeper's office at the various navy yards. Any indi-

cation of the use of rosin or any other adulterant in this

varnish will be sufficient for its rejection.

The paste wood filler when thinned with turpentineto a brushing consistency must dry hard on glass in 24

hours. It must not rub up by friction under the finger,

and when immersed in water must remain intact for at

least 4 hours. It must dry full without luster, and

be transparent, so that it will not color or cloud the

work, and be hard enough to stand sandpaper without

clogging the paper after 12 hours.

CHAPTER XI.

ANALYSIS OF WHITE LEAD.

165. Color. The two samples are weighed out in gramlots on a large glass plate, twelve drops of bleached

linseed oil added to each and rubbed up thoroughly, and

matched up on a microscope slide, the color being

judged from both sides of the glass. After comparingthe color, place the slide in the steam oven for two

hours. This will give some idea as to the amount of

yellowing that will occur when the lead is used in paint-

ing. This defect is particularly marked in pulp leads.

166. Opacity. Two grams each of the sample and

standard are very carefully rubbed up with .01 gramof ultramarine blue and twenty-four drops of oil as

described under the section on the" Determination of

the tinting strength of colors." The more strongly the

lead is colored, the weaker it is in hiding power or opac-

ity. Adding weighed amounts of lead until the colors

are of equal depth will show the ratio between the two.

167. Painting test. The painting value is best judged

by painting test boards, as described under the section

on the"Comparison of paints for covering power," and

afterwards exposing them under suitable conditions.

168. Sulphur dioxide. In the manufacture of quick-

process white leads, where the carbon dioxide is obtained

from fuel gases, it is liable to contain sulphur compoundswhich will remain in the white lead combined in the

form of sulphite of lead.

169. The sulphur dioxide may be estimated by treat-

ing 10 grams of the pigment with 50 c.c. of water and92

ANALYSIS OF WHITE LEAD. 93

25 c.c. of hydrochloric acid. Allow to stand 5 minutes

and titrate with a hundredth normal iodine solution as

described under the estimation of sulphur dioxide in

zinc pigments. The same objections apply to its pres-

ence in white lead as in zinc oxides.

170. Sandy lead. 1 "A. certain degree of density is

always desired in white lead, since both the corroder

and the grinder know that the smaller the amount of oil

required to bring a given lead to paste form, the cheaperit is for him, since the average price per pound of lin-

seed oil is greater than that of dry lead, while the same

pigment is equally sought after by the consumer, since

he, too, desires density and opacity in this pigment.

However, efforts in this direction are not infrequently

carried too far, with the result of a crystalline over-

corroded lead which settles and hardens badly. Such

lead causes loss and trouble both to the grinder and the

consumer."

171. Determination." Based upon the undesirable fea-

ture of settling, a comparative separation is easily made.

A fairly large sample, say 100 grams, is taken. This, if

in paste form, is thinned with benzine and run througha fine bolting cloth. Any paint skins are retained, but

all of the lead should, when sufficiently thinned, wash

through a fine bolting cloth. The very thin paint is

now thoroughly stirred and allowed to settle for only a

short time. Nearly all of the benzine is now poured off

and then the washing of the sediment with benzine is re-

peated until the benzine comes off nearly clear, leavingthe 'sand' alone as a residue." While present in all

commercial lead, the amount should be small, scarcely

exceeding 2.5 per cent; objectionable samples will fre-

quently show much more, at times over 10 per cent.

1Hooker, Treatise on White Lead, page 24.


172. Tanbark. The determination of tanbark and

other organic matter is seldom required. It may, how-

ever, be made by dissolving 50 grams of the sample in

75 c.c. of nitric acid diluted with 250 c.c. of water.

Filter through .a weighed Gooch crucible, provided with

a disk of filter paper on the top of the asbestos felt,

wash thoroughly, dry, and weigh. The amount present

should not exceed one-tenth of one per cent, according

to Hooker.

173. Sulphate of lead, which may be present in someof the quick-process leads, would largely remain undis-

solved in the nitric acid solution and unless removed

would be weighed up as tanbark, etc. When present

it may be dissolved by placing the Gooch crucible and

contents in a small beaker containing acid ammoniumacetate for a few minutes, after which the crucible is

placed in the holder, washed with a further quantity of

acetate solution, then with a little warm water, and

dried as before.

174. Metallic lead. Like the determination of sandylead it is seldom made. Occasionally in poorly preparedwhite leads a sufficient amount may be present to war-

rant a determination, in which case it is best made in

conjunction with the determination of"sandy lead,"

which, after being weighed up, is carefully dissolved in

dilute nitric acid, the operation being checked the mo-ment the sandy white lead has dissolved by dilution

with a large quantity of water. The particles of metal-

lic lead are but very slightly acted upon by acid and

may be filtered off on a weighed Gooch crucible, washed

thoroughly, dried, and weighed. The amount found

should not exceed one-tenth of 1 per cent.

175. Lead sulphate. This impurity may be present in

small quantities in white leads prepared by the newer


processes and sometimes in old Dutch process lead in

the settling tanks and wash-water tanks. When present

in quantities less than one-half of 1 per cent it should

not be considered as seriously objectionable.

176. Determination. Dissolve 1 gram in water 25 c.c.,

ammonia 10 c.c., hydrochloric acid in slight excess.

Dilute to 200 c.c., and add a piece of aluminum foil

which should about cover the bottom of the beaker.

It is important that this be held at the bottom by a

glass rod. Boil gently until the lead is precipitated.

Completion of this is shown by the lead ceasing to coat

or cling to the aluminum. Decant through a filter,

pressing the lead sponge into a cake to free it from solu-

tion. Add to nitrate a little sulphur-free bromine water,boil until the bromine is expelled, add 15 c.c. of barium

chloride, boil 10 minutes, filter, wash with hot water,

ignite, and weigh as barium sulphate. Calculate to lead

sulphate by multiplying by 1.3 as a factor.

177. Volumetric estimation of lead, Method I.1 Dis-

solve 1 gram in 15 c.c. nitric acid, specific gravity 1.20,

neutralize the solution with ammonia in excess, andthen make strongly acid with acetic acid. It is then

boiled and standard potassium bichromate solution is

run in from a burette in sufficient quantity to precipi-

tate nearly all the lead. The liquid is boiled until the

precipitate becomes orange colored. The titration is

continued, one-half cubic centimeter or so at a time, the

solution being well stirred after each addition of bichro-

mate until the reaction is almost complete, which can

be observed by the sudden clearing up of the solution,

the lead chromate settling promptly to the bottom of

the beaker; this will usually occur within 1 c.c. of the

end of the reaction. The titration is then finished, the

Wainwright, J. Am. Chem. Soc., Vol. XIX, page 389.


end point being indicated by the use of silver nitrate

as an outside indicator, on a white plate.

The solution of the lead salt should be as concen-

trated as possible before titration and decidedly acid

with acetic acid. The titration should be performed in

a solution kept at all times as near the boiling point as

possible.

178. Potassium bichromate solution. This should be

of such strength that 1 c.c. equals approximately 0.01

gram of metallic lead, and should be standardized

against a weighed amount of pure metallic lead as de-

scribed above.

179. Silver nitrate solution. Dissolve 2.5 grams of

silver nitrate in 100 c.c. of water.

NOTE. This method is applicable for determination of lead in red

lead, the solution being effected with nitric acid, boiling, and addingdilute oxalic acid drop by drop until the lead oxide formed is completlydissolved.

180. Volumetric estimation of lead, Method II. 1 Dis-

solve 0.5 to 1 gram of the pigment in acetic acid if

white lead; if lead sulphide, dissolve in nitric acid, dilute

with 25 c.c. cold water, add strong ammonia until just

alkaline to litmus paper, then make distinctly acid

with strong acetic acid.

181. Heat to boiling, dilute to about 200 c.c. with

boiling hot water, and titrate with standard ammonium

molybdate solution. Reserve about 10 c.c. of the hot

solution in a small beaker, run in molybdate solution

into the large beaker from a burette, with constant stir-

ring, until a drop placed in contact with a drop of tannic

acid solution on a white plate gives a brown or yellow

tinge. Add the 10 c.c. reserved and finish the titration

carefully at the rate of two drops addition at a time.

1 Alexander's Method, Ore Analysis, Low, page 113.

ANALYSIS OF WHITE LEAD 97

When the final yellow tinge is obtained, it is probable

that some of the immediately preceding test drops mayhave developed a tinge also. If such is the case deduct

the volume of two drops from each test showing a color

from the final burette reading.

182. Molybdate solution. Prepare a solution of am-monium molybdate 1 c.c. of which is equal to approxi-

mately .01 gram of lead. Standardize against a weighedamount of chemically pure lead, dissolving in nitric

acid and treating as described above.

183. Tannic acid solution. Dissolve 0.5 gram of tannic

acid in 100 c.c. of water.

184. Carbon dioxide. The amount of carbon dioxide

in white lead can be most accurately estimated by meansof Knorr's apparatus.

FIG. 5. KNORR'S APPARATUS.

This apparatus employs only ground-glass joints, and

may be quickly made ready for use or taken to piecesand packed away. On the other hand, it is inflexible

and must be carefully handled. A is a distilling flask

fitted to a condenser by a ground-glass stopper; B, reser-

voir containing acid; C, soda-lime tube; D, condenser;

E, calcium chloride tube; F, U-tube filled with pumice


stone moistened with sulphuric acid, followed by a

calcium-chloride tube G. The three soda-lime tubes

H, H, ff are followed by a calcium chloride tube K,which is connected with an aspirator at L.

The calcium chloride and soda lime employed should

be finely granulated and freed from dust with a sieve.

185. One gram of the sample to be examined is

placed in the distilling flask, which must be perfectly

dry. The flask is closed with a stopper carrying the

tube connecting with the absorption apparatus and also

with the funnel tube. The tubes in which the carbon

dioxide is to be absorbed are weighed and attached to

the apparatus. In case two Liebig bulbs are employed,one for potassium hydroxide and the other for sulphuric

acid, to absorb the moisture given up by the potassium

hydroxide solution, it will be necessary to weigh them

separately. If soda-lime tubes are employed it will be

found advantageous to weigh them separately and fill

the first tube anew when the second tube begins to in-

crease in weight materially. The bulb B is nearly

filled with hydrochloric acid (sp. gr. 1.1), and the guardtube C placed in position. The aspirator is now started

at such a rate that the air passes through the Liebig

bulbs at the rate of about two bubbles per second.

The stopper of the funnel tube is opened and the acid

allowed to run slowly into the flask, care being taken

that the evolution of the gas shall be so gradual as not

materially to increase the current through the Liebigbulb.

186. After the acid has all been introduced, the as-

piration is continued, when the contents of the flask are

gradually heated to boiling, the valve in tube B beingclosed. While the flask is being heated the aspirator

tube may be removed, although many analysts prefer


when using ground-glass joints to aspirate during the

entire operation. The boiling is continued for a few

minutes after the water has begun to condense in Z),

when the flame is removed, the valve in the tube Bopened, and the apparatus allowed to cool with con-

tinued aspiration. The absorption tubes are then re-

moved and weighed, the increase in weight being due to

carbon dioxide.

187. When extreme accuracy is desired the carbon

dioxide after passing through the condenser should pass

through a U-tube filled with calcium chloride, a U-tube

filled with lumps of dehydrated copper sulphate mois-

tened with sulphuric acid (sp. gr. 1.84), and then througha U-tube filled with pumice stone moistened with sul-

phuric acid before being absorbed by soda lime. Theair used for aspirating should also pass through a

large U-tube filled with soda lime before passing throughthe small soda-lime tube C. In order to make the ap-

paratus compact the soda-lime tubes may be laid side

by side on a small rack constructed for the purpose, the

soda-lime tubes being connected with one another bysmall U-shaped glass tubing connections.

188. Acetic acid in white lead.1 "In the manufacture

of white lead by any process involving the use of acetic

acid, a certain portion of the acetic acid seems to be

bound firmly so that it cannot be washed out in anyordinary process of manufacture. The amount of the

acetic acid which is fixed by the white lead depends

largely upon the quantity used in the process of manu-facture. The navy yard specifications demand a

white lead which shall not contain'

acetate in excess of

fifteen one-hundredths of 1 per cent of glacial acetic

acid.' It seems reasonable, furthermore, that whether1 G. W. Thompson, J. Soc. Chem. Ind., Vol. XXIV, No. 9.


the acetic acid is objectionable or not, the intelligent

purchaser of white lead should be enabled, as far as

possible, to know what he is buying, and perhaps to

trace back results to some definite cause/'

189."Ordinary lead acetate solution will take up

varying amounts of lead oxide to form basic lead ace-

tate. The more concentrated the lead acetate solution

is, the less basic will be the formed acetate;for instance,

the ordinary pharmacopoeia solution'

Liquor Plumbi

Subacetatis' - contains two equivalents of lead to one

of acetic acid, and, while this solution may be mademore basic than this by adding an excess of litharge, the

amount of litharge which it will take into solution in

excess of that required to form the pharmacopoeia solu-

tion is comparatively small."

190."Working with dilute solutions of lead acetate,

however, solutions can be obtained containing as muchas ten equivalents of lead to one of acetic acid. These

very basic dilute solutions may, however, be regarded

by some as supersaturated solutions, for the reason

that the basic lead tends to separate out on slight provo-

cation, carrying with it some acetic acid. If this verybasic lead acetate which separates out is washed with

distilled water, it appears to form a colloidal solution

from which the basic lead is readily precipitated in the

presence of suspended inert material, and especially

in the presence of electrolytes. Ordinary water is

usually used for washing white lead, and, as this water

contains more or less saline substances, any of this

extremely basic acetate that is present will be precip-

itated with the white lead, and go into the finished

product."

191. Determination. "18 grams of the dry white lead

are placed in a 500-c.c. flask, this flask being arranged

ANALYSIS OF WHITE LEAD-.. 101

for connection with a steam supply, and also with an

ordinary Liebig condenser. To this white lead is added

40 c.c. of sirupy phosphoric acid, 18 grams of zinc dust,

and about 50 c.c. of water. The flask containing the

material is heated directly and distilled down to a small

bulk. Then the steam is passed into the flask until it

becomes about half full of condensed water, when the

steam is shut off and the original flask heated directly

and distilled down to the same small bulk, this opera-tion being conducted twice. The distillate is then trans-

ferred to a special flask and 1 c.c. of sirupy phosphoricacid added to insure a slightly acid condition."

192. "The flask is then heated and distilled down to

a small bulk say 20 c.c. Steam is then passed

through the flask until it contains about 200 c.c. of con-

densed water, when the steam is shut off and the flask

heated directly. These operations of direct distillation

and steam distillation are conducted until 10 c.c. of

the distillate require but a drop of N/10 alkali to pro-

duce a change in the presence of phenolphthalein.

Then the bulk of the distillate is titrated with N/10sodium hydroxide, and the acetic acid calculated. It

will be found very convenient in this titration, which

amounts in some cases to from 600 to 700 c.c., to titrate

the distillate when it reaches 200 c.c., and so continue

titrating every 200 c.c. as it distills over.

193. Conclusions." The details in this described

method, as regards the supply of steam from an outside

flask, its condensation and subsequent evaporation, are

not essential to the process, but can, of course, be modi-

fied so as to conform to the ordinary method of distill-

ing acetic acid from acetate of lime. If the white lead

contains appreciable amounts of chlorine, it is well to

add some silver phosphate to the second distillation

102 PAlfrT AND VARNISH PRODUCTS.

flask, and not to carry the distillation from this flask

too far at any time. If the dry white lead under ex-

amination has been obtained by the extraction as a

residue from white lead paste, it is well that this extrac-

tion should be exceedingly thorough, as otherwise fatty

acids may be held and distilled with the acetic acid.

Even then they will not interfere with the final titra-

tion, as they may be filtered from the distillate before

titration, should that be desired."

194. ANALYSES OF MISCELLANEOUS WHITE LEADS MADEBY THE AUTHOR.

None of the above products are entitled to be called

white lead. Only one bore the name of the companyputting out the product.

195. Short weights of white lead packages. All the white

leads and so-called white leads, examined by the writer,

have been found to be short weight. That is, the kegs

supposed to contain 12| pounds will actually contain, in

each eight kegs which should have shown 100 pounds,

only 83 to 89 pounds. As showing to what extent the

different so-called white leads actually varied and fell

short in weight, I give the following list :

CHAPTER XII.

ANALYSIS OF SUBLIMED WHITE LEAD AND THE ZINCPIGMENTS.

196. The analysis of sublimed white lead. 1 Lead and

Zinc Oxide. Weigh 1 gram into a small beaker, add

20 c.c. of 10 per cent sulphuric acid, stir well, and allow

to stand 10 minutes, filter, and wash slightly with dilute

sulphuric acid on filter.

Residue. Dissolve through filter with hot, slightly

acid ammonium acetate solution, wash with hot water,

and dilute to 200 c.c. with hot water. Add a slight

excess of potassium bichromate solution and heat.

Filter on Gooch crucible, wash with water. Dry, ignite,

and weigh as lead chrornate.

Filtrate. Add about 2 grams of ammonium chloride,

heat to boiling, add excess of ammonia, and filter. Re-

ject residue. Add 1 gram of microcosmic salt and a

very slight excess of acetic acid. Boil, cool, filter on

Gooch crucible, and wash with water. Ignite, and

weigh as zinc pyrophosphate. Calculate to zinc oxide.

197. Sulphates. Dissolve 0.5 gram in water 25 c.c.,

ammonia 10 c.c., hydrochloric and in slight excess.

Dilute to 200 c.c. and add a piece of aluminum foil

which should about cover the bottom of the beaker. It

is important that this be held at the bottom by a glass

rod. Boil gently until the lead is precipitated. Comple-tion of this is shown by the lead ceasing to coat or cling

to the aluminum. Decant through a filter, pressing

1 The author is indebted to L. S. Hughes of the

Lead Company for this method.

104

SUBLIMED WHITE LEAD AND ZINC PIGMENTS. 105

the lead sponge into a cake to free it from solution.

Add to filtrate a little sulphur-free bromine water, boil,

and precipitate as barium sulphate in the usual manner.

198. Sulphur dioxide. Treat 2 grams with 5 per cent

Nsulphuric acid and titrate with - iodine. A quick

100

method of calculating the lead sulphate and oxide from

the above data is the following : Multiply the weight of

barium sulphate from 1 gram by 1.3, which gives the

weight of lead sulphate. Multiply the same weight of

barium sulphate by 0.088 and deduct this result from

the total lead found. Multiply the difference by 1.077,

which will give the lead oxide.

199. Composition of sublimed white lead. The ap-

proximate composition of sublimed lead as stated bythe manufacturers is as follows:

Per cent.

Lead sulphate 75Lead oxide 20Zinc oxide 5

100

The lead sulphate and lead oxide are apparently com-

bined as a white oxysulphate. The zinc oxide is inci-

dental to the manufacture.

ANALYSES OF SUBLIMED WHITE LEAD BY THEAUTHOR.

I. II.

Per cent. Per cent.

Lead sulphate 75.02 80.29Lead oxide 18.48 14.46Zinc oxide 6 . 22 5 . 18Silica and alumina 0.28 0.07

100.00 100.00

200. Sublimed blue lead. This pigment, which has a

grayish blue color, is obtained in much the same wayas sublimed white lead. Its variable and complex


composition, however, limits its use. The following is

an analysis published by Mannhardt: 1

Per cent.

Lead sulphate 41.72Lead sulphite

'

7.55Lead sulphide 10 . 76Lead oxide. ; 29.03Zinc oxide 2.84Calcium oxide . . . 2 . 88

Magnesium oxide . 80Ferric oxide . 40Carbon dioxide 0.86Carbon 2.50Bitumen : . . 0.34Moisture . 0.50

100.18

201. The identification and estimation of sublimed white

lead in mixtures. 2 Neutral ammonium chloride solution

will dissolve the lead compounds of sublimed white lead;

also the hydrate of corroded white lead, zinc oxide, and

some calcium sulphate. It leaves undissolved calcium

carbonate, zinc sulphide, normal lead carbonate, and

the content of lead carbonate in corroded lead.

To determine the sublimed white lead in a pigment

containing the above ingredients, boil the sample with

a considerable excess of strong neutral ammonium chlo-

ride solution, filter hot on the pump, and wash with hot

dilute neutral ammonium chloride.

202. The lead, zinc, lime, and sulphuric anhydride are

determined in the filtrate. The required sulphur tri-

oxide is combined with the lime and the rest with the

lead. Any excess of lead is contingent in its application

upon the amount of lead found undissolved by the

ammonium chloride.

If there is an appreciable amount of this residual

carbonate, the required hydrate is calculated, and a

1Drugs, Oils and Paints, August, 1909.

2 The author is indebted to L. S. Hughes for this method.


deduction made from the excess lead found in the nitrate.

Any lead in the original nitrate not satisfied is now cal-

culated to lead oxide and regarded as the lead oxide of

sublimed white lead, and the lead sulphate and zinc

oxide thereof calculated and deducted from the total of

these compounds.It will be noted that the conditions above considered

are much more complex than need be anticipated in the

analysis of actual paints.

Extraction of lead sulphate by the above treatment

prevents the necessity of considering the sulphuric an-

hydride of possible barium sulphate, and leaves the

original residue in such shape that if it contains both

the carbonate and sulphate of barium they can be con-

veniently separated.

Analysis of Zinc Pigments.

203. Moisture. Two grams of the pigment are

weighed out on a watch glass, provided with a cover

glass and clip, dried for two hours in a steam oven, the

cover glass placed in position and held by the clip, 'the

glasses cooled in the desiccator and weighed. Loss

in weight represents the amount of moisture in the

pigment.

204. Silica. Weigh 1 gram of pigment into a 250-c.c.

covered beaker, add 25 c.c. of concentrated hydro-chloric acid, heat gently for five minutes, or until

the pigment has dissolved (if lead sulphate is present

in considerable quantity this may take quite a few

minutes), add 50 c.c. hot water, and continue the

heating for about five minutes longer. Filter boiling

hot with the aid of suction, washing thoroughly with

boiling water so as to remove all the lead and zinc

salts from the filter paper. The filter paper and any


residue of silica is burned, ignited, and weighed in the

usual manner. Any weighable residue is reported as

silica.

205. This treatment may give results that are slightly

low, owing to . the slight solubility of silica in strong

hydrochloric acid, but for commercial purposes this

slight error may be neglected. In carefully preparedzinc pigments the amount of silica present will be un-

weighable; even with careless processing the amountwill seldom exceed a very few hundredths of 1 percent.

206. Sulphur dioxide. Weigh 3 grams of the pigmentinto a 250-c.c. beaker; add 100 c.c. of distilled water,

that has been recently boiled and cooled. Add 5 c.c. of

concentrated sulphuric acid, stir thoroughly, and allow

to stand 15 minutes. Titrate with standard hun-

dredth normal iodine solution, using starch paste as

an indicator.

1 c.c. hundredth normal iodine = 0.00032 gram sul-

phur dioxide.

207. Preparation of reagents Iodine solution. Dis-

solve 1.268 grams of pure iodine and 1.8 grams of po-tassium iodide in about 150 c.c. of water in a graduatedliter flask. After solution, fill to the mark with water

that has been freshly boiled.

208. Sodium thiosulphate. Dissolve 2.5 grams in re-

cently boiled distilled water and make up to 1 liter.

Preserve in a brown glass bottle or one that has received

a liberal coat of asphaltum.

209. Starch paste. One gram of starch is boiled in

200 c.c. of distilled water.

210. Standardizing the sodium thiosulphate solution.

Pipette 20 c.c. of standard potassium dichromate solu-

tion in a 250-c.c. beaker; add 10 c.c. of a 15-per cent


solution of potassium iodide. Add 10 c.c. of a 15-per

cent solution of potassium iodide. Add to this 5 c.c.

of strong hydrochloric acid. Allow the solution of thio-

sulphate to run in slowly from a burette until the yellow

color has almost disappeared. Add a few drops of

starch paste and continue the addition of thiosulphate

with constant stirring until the blue color just disap-

pears. The burette reading is then made and the

value of the thiosulphate calculated.

211. Standard of acceptance. A good grade of zinc

oxide should contain only a trace of sulphur dioxide.

Many paint chemists reject oxides containing more than

six hundredths of one per cent. The reason for this is

that the sulphur dioxide affects the character of the

linseed oil very strongly, causing the paint to thicken

and ultimately"liver" in the package. This may be

shown in an experimental way by dividing a sample of-

zinc oxide into two parts, exposing one part to an at-

mosphere of sulphur dioxide, then spreading equal

amounts of both samples on a glass plate and mixingto a paste with the same number of drops of oil in ex-

actly the same manner. It will be found that the

sample containing the sulphur dioxide will be thicker

and stiffer than the other, showing the effect of the

sulphur dioxide on the oil.

212. Reaction with rosin products. In the presence of

rosin products of any kind, such as are often used in the

driers of mixed paints, sulphur dioxide acts as a contact

agent of great strength, causing changes all out of pro-

portion to the amount present, often resulting in hard-

ening,"washing" of the paint film, "livering" in the

package, etc. These results will be influenced to a

considerable degree by the acidity, moisture, and

temperature of the paint, and hence no hard and fast


deductions can be made as to what may be expectedof any particular paint containing sulphur dioxide in

excess of the prescribed amount.

213. Zinc sulphate. Ten grams of the pigment are

weighed into a 250-c.c. Erlenmeyer flask and 100 c.c. of

boiling water added. The contents of the flask are then

shaken thoroughly for several minutes and filtered and

the residue on the filter paper washed with several por-

tions of boiling water. The soluble zinc in the filtrate

is then titrated as described under the" Estimation of

Zinc"by titration with ferrocyanide, and calculated to

zinc sulphate.

214. It is not advisable to boil zinc oxide pigmentswith the water, as interaction may occur between the

zinc oxide and any lead sulphate present, resulting in

the formation of more zinc sulphate. Neither is it wise

.to estimate the soluble combined sulphuric acid in the

hot aqueous filtrate and calculate to zinc sulphate, as

there often seems to be an excess over what is required

to form the normal sulphate of zinc and hence the re-

sults are apt to be too high.

215. Effect. Zinc sulphate is not considered by manypaint chemists to be so objectionable in zinc pigmentsas sulphur dioxide, and is often permitted in amounts

under 1 per cent. In amounts above 1 per cent it

seems to act as an astringent on the oil when used in

the preparation of mixed paints, tending to prevent the

proper penetration of the wood, especially if the paint

has been ground for some length of time. A prominent

paint chemist discusses its effect as follows: "The action

of zinc sulphate is twofold : first, as an astringent uponthe oil and tending to cause a distinct demarcation

between two coats;and second, that of a contact agent,

facilitating reaction between the different pigments.

SUBLIMED WHITE LEAD AND ZINC PIGMENTS. Ill

The visible results of its presence are peeling and 'wash-

ing.' Apparently, rather more than the normal amount

of moisture must be present to cause its activity, and if

the paint coat has set under dry or normal conditions,

the zinc sulphate produces no apparent effect." In the

exposure tests conducted by the author, the worst cases

of "washing" have occurred with zinc pigments in

which the sulphur dioxide was less than one-hundredth

of 1 per cent and the zinc sulphate between 1 and li

per cent.

216. Lead. The lead present in zinc pigments is usu-

ally in the form of sulphate and may be estimated byeither of the following methods.

217. Method I. The filtrate from the silica, which need

not exceed 100 c.c. in volume if the washing has been

judiciously conducted by suction or the hydrochloric

acid solution is absent, is evaporated very nearly to

dryness in an uncovered beaker on the hot plate, avoid-

ing actual boiling, 10 c.c. of warm water added, and

evaporated again nearly to dryness in order to expel

the hydrochloric acid. Cool, add 30 c.c. dilute sul-

phuric acid, heat to boiling for five minutes in a covered

beaker, cool, add 50 c.c. of alcohol, and allow to stand

one-half hour or until all of the lead sulphate is precipi-

tated from solution. Filter through a weighed Gooch

crucible, washing thoroughly with 50 per cent alcohol,

until the precipitate is entirely freed from zinc sulphate.

Dry on hot plate, heat gently over a Bunsen burner,

cool in desiccator, and weigh as lead sulphate. If

heated over the flame before drying, a portion of the

lead is liable to be reduced to lead oxide by the alcohol,

and the weight will be low.

218. Method II. The lead may be separated from the

zinc in a solution barely acid with hydrochloric acid, by


hydrogen sulphide, the precipitated lead sulphide dis-

solved in nitric acid and titrated with standard molyb-date or bichromate solution, as described in Chapter

XVI, Analysis of White Paints.

219. Method III. The amount of lead sulphate maybe rapidly estimated by dissolving a weighed amount of

the pigment in dilute acetic acid, filtering on to a

weighed Gooch crucible, washing with warm water,

heating gently, and weighing the lead sulphate direct.

Lead sulphate being slightly soluble in acetic acid the

results will be somewhat low and can only be consid-

ered as roughly approximate.220. Total zinc. The zinc can be rapidly and ac-

curately estimated volumetrieally by the following

methods.

221. Potassium ferrocyanide method. Preparation of

reagents.

222. Standard zinc solution. Dissolve 10 grams of

chemically pure zinc in hydrochloric acid in a gradu-ated liter flask, add 50 grams of ammonium chloride,

and make up to 1 liter.

1 c.c. = 0.01 gram zinc or 0.01245 gram zinc oxide.

223. Standard potassium ferrocyanide solution. Dis-

solve 46 to 48 grams of crystallized potassium ferrocya-

nide in water, make up to 1000 c.c.

224. Uranium nitrate solution. Dissolve 15 grams of

uranium nitrate in 100 c.c. of water.

225. Standardizing the ferrocyanide solution. To de-

termine the value of the potassium ferrocyanide solu-

tion, pipette 25 c.c. of the zinc solution into a 400-c.c.

beaker. Dilute somewhat and make faintly alkaline

with ammonia, bring to a faintly acid condition with

hydrochloric acid, and then "add 3 c.c. excess of the

concentrated acid, dilute to a total volume of about


250 c.c., heat to 80 C., and titrate as follows: Pour off

about 10 c.c. of the zinc solution into a small beaker

and set aside, run the ferrocyanide into the remainder

from a burette, a few cubic centimeters at a time,

until the solution takes on a slight ash-gray color, or

until a drop of the solution placed in contact with a

drop of the uranium nitrate solution on a porcelain

plate turns to a distinct brownish color.

226. Often the end point has been passed by quite a

little. The 10 c.c. of zinc solution that has been re-

served is now added and the titration continued, drop

by drop, testing a drop of the solution carefully on

the porcelain plate after each addition of ferrocyanide

solution. Some little time is required for the test

drop to change color, so that the end point may have

been passed slightly; this may be corrected for bymaking a memorandum of the burette readings, havingthe test drops arranged in regular order, and taking as

the proper reading the one first showing a distinct

brownish tinge. Having noted the number of cubic

centimeters ferrocyanide required for the titration of

the standard zinc solution, the value of 1 c.c. may be

readily calculated.

227. Titration of sample. One-half gram of the sampleif high in zinc, or 1 gram if the zinc content is fairly low,

is dissolved in a covered beaker in 10 c.c. of hydro-chloric acid and 10 c.c. of water, the solution diluted

somewhat, neutralized with ammonia, and treated ex-

actly as described above for the standard zinc solution,

care being taken to titrate to exactly the same depthof color on the porcelain test plate. If the method is

carefully carried out, the procedure being uniformlythe same in each determination, the results will be

found satisfactorily accurate.


228. Combined sulphuric acid. Dissolve 0.5 gram to

1 gram of the pigment, according to the amount of

sulphates present, in

Water, 25 c.c.

Ammonia, 10 c.c.

Hydrochloric acid, a slight excess.

229. Dilute to 200 c.c. and add a disk of aluminum

foil, which should about cover the bottom of the beaker.

Boil gently until the lead is precipitated, holding the

disk if necessary to the bottom of the beaker with a

glass rod. The completion of precipitation is shown

by the lead ceasing to coat or cling to the aluminum.

Decant through a filter, pressing the lead sponge into

a cake and washing thoroughly to free from solution.

230. Add to the filtrate a few drops of bromine water,

boil, and precipitate with barium chloride in the usual

manner for sulphates. In order to avoid a possible

reduction of a portion of the barium sulphate in the

pores of the filter paper during its incineration, the

precipitate may be filtered directly on to a Gooch

crucible, which after being weighed has a disk of ash-

less filter paper placed on top of the customary asbestos

felt. This will effectually prevent any of the precipi-

tate from burrowing through the filter. The ignition

of the precipitate in the presence of the small disk

of filter paper will cause no appreciable reduction to

sulphide.

231. Calculations. The amount of zinc present as sul-

phate of zinc is deducted from the total zinc and the

remainder calculated to zinc oxide. The sulphuric acid

combined with the zinc is deducted from the total com-

bined sulphuric acid and the remainder calculated to

lead sulphate. Any excess of lead over that required


to combine with the sulphuric acid is calculated to

lead oxide. Unless sublimed lead is present there will

be little or no lead oxide.

Undoubtedly new sulphate of lead pigments will be

placed on the market within the next few years which

will be entirely different from those discussed, and in

such instances careful determinations of the service

values should be made apart from the chemical exam-

ination.

CHAPTER XIII.

ANALYSIS OF SUBLIMED WHITE LEAD AND THE ZINCPIGMENTS (continued).

232. Zinc white. It was formerly the custom to offer

reduced zinc oxides in oil, i.e., combination zincs under

the name of zinc white, the different grades being dis-

tinguished by the use of such terms as" Green Seal,

Red Seal," etc. Until the passage of suitable paintlaws the purchaser had no means of knowing what he

was obtaining, any more than he did in the case of

combination leads which had hitherto been sold under

the simple designation white lead. It is now customaryfor paint manufacturers to offer reduced zinc oxides

under an explanatory designation like the following:

Zinc White.

In combination with reinforcing pigments. Groundin pure linseed oil. 12| Ibs. net weight.

Analysis. Per cent.

100.00

233. The analysis of reduced zinc oxides offers no

difficulties except that when ground in varnish the

determination of the constitution of the varnish will

require careful consideration. Usually the varnish will

be found to be dammar cut with turpentine or naph-tha or both, and may be used in conjunction with

varnish oil (a specially prepared linseed oil).

116


234. The following analyses are characteristic of the

zinc whites on the market :

i. n. in.

Per cent. Per cent. Per cent.

Zinc oxide 53.93 69.61 61.83Barium sulphate 35.96 18.99 8.03Linseed oil 10.11 11.40 2.00

Turpentine 14 . 35

Dammar gum 13 . 79

100.00 100.00 100.00

235. Estimation of arsenic and antimony in zinc leads.

Weigh 2 grams of the sample into a 200-c.c. digestion

flask. Add 7 grams of potassium bisulphate, 0.5 gramof tartaric acid, and 10 c.c. of concentrated sulphuric

acid. Digest carefully at first, but finally with the

full power of a Bunsen burner until a clear mass re-

mains, containing but little free sulphuric acid. Cool,

spreading the melt around on the sides of the flask.

Add 50 c.c. of water, 10 c.c. of strong hydrochloric acid,

and digest for about twenty minutes without boiling.

236. Cool thoroughly under the tap and filter off the

separated lead sulphate. Dilute the filtrate to about

300 c.c. with hot water, maintain the liquid warm, and

pass in hydrogen sulphide for about fifteen minutes or

until precipitation is complete. Filter, washing with

hydrogen sulphide water. Digest filter and contents

in a rather small amount of yellow ammonium sul-

phide. Filter on suction cone, washing with as small

a quantity of water as possible.

237. Digest the filtrate with 3 grams of potassium*

bisulphate and 10 c.c. of strong sulphuric acid over a

free flame until all of the free sulphur and the larger

portion of free acid are expelled. Cool, spreading the

melt around on the sides of the flask as before. Add25 c.c. of water and 10. c.c. of strong hydrochloric acid,

and warm to effect complete solution. Cool under the


tap, add 40 c.c. of strong hydrochloric acid, and passin hydrogen sulphide until complete precipitation of

the arsenic takes place, 15 to 30 minutes. The

antimony remains in solution.

238. Filter off the precipitated arsenious sulphide on

to a weighed Gooch crucible, washing with a mixture of

two volumes of hydrochloric acid and one of water.

The filtrate is reserved at this point for the estimation

of antimony. The precipitate is next washed with

alcohol, the crucible and contents placed in a small

beaker, the crucible nearly filled with carbon bisul-

phide, (and the contents allowed to digest at ordinary

temperature for about twenty minutes in order to

dissolve the free sulphur. The carbon bisulphide is

removed by suction, the crucible dried in the steam

oven, cooled, and the precipitate weighed as arsenious

sulphide and calculated to arsenious oxide.

Weight arsenious sulphide X 0.8043 = weight arse-

nious oxide.

239. Instead of weighing as the sulphide, the arsenic

may be estimated volumetrically as follows: Wash out

the hydrochloric acid from the sulphide precipitate

with hydrogen sulphide water. Digest filter and con-

tents in a little warm ammonium sulphide, filter on a

suction cone, washing with a little dilute ammonium

sulphide solution. Place the filtrate in digestion flask,

add 2 to 3 grams of potassium bisulphate and 5 c.c. of

strong sulphuric acid. Evaporate, boiling to a small

bulk, and then manipulate the flask over a free flame

until the sulphur is entirely expelled and most of the

free acid also. Take up, after cooling, by warmingwith 50 c.c. of water, and then boil sufficiently to expel

any possible sulphur dioxide. Now drop in a bit of

litmus paper as an indicator, and then add ammonia


until the solution is slightly alkaline. Again slightlyacidify with hydrochloric acid and cool to room tem-perature. Finally, add 3 to 4 grams of sodium acidcarbonate and a little starch liquor and titrate withstandard iodine solution. Pay no attention to a slightdiscoloration toward the end, but proceed slowly untila single drop of the iodine produces a strong permanentblue color.

240. Preparation of iodine solution. The iodine solu-tion may be prepared by dissolving about 11 grams ofiodine in a little water with the addition of about 20grams of potassium iodide and diluting to 1 liter.

Standardize with arsenious oxide. Dissolve about 0. 150gram in 5 c.c. of strong hydrochloric acid by warmingvery gently, dilute and neutralize as described above,and finally titrate with the iodine solution. 1 c.c. ofthe latter will equal about 0.003 gram of arsenic.

241. Antimony. Very nearly neutralize the filtratereserved for the antimony estimation with hydrochloricacid, dilute with double its volume of hot water, andpass in hydrogen sulphide until all of the antimony is

precipitated. Filter, washing with hydrogen sulphidewater. Digest filter and contents in a little ammoniumsulphide, filter on suction cone, and wash with diluteammonium sulphide. Place the filtrate in the diges-tion flask and add about 3 to 4 grams of (pure) potas-sium bisulphate and 10 c.c. of strong sulphuric acid.Boil as previously described to expel first the water,then all the free sulphur, and finally most of the freeacid.

242. Cool, add 50 c.c. of water and 10 c.c. of stronghydrochloric acid. Heat to effect solution, and then boilfor a few minutes to expel any possible sulphur dioxideFinally add 10 c.c. more of strong hydrochloric


acid, cool under the tap, dilute to about 200 c.c. with

cold water, and titrate with a standard solution of

potassium permanganate. The solution ordinarily used

for iron titrations will answer. The oxalic acid value

of the permanganate multiplied by 0.9532 will give the

antimony value.

243. Methods of determining small amounts of arsenic

and antimony in use at Canon City, Colorado. Method I.

Take two or three grams of pigment and dissolve in

10 c.c. nitric acid and 10 c.c. sulphuric acid. Heat to

expel the nitric acid and evaporate to sulphuric fumes.

The advantage of the nitric acid is to oxidize the arsenic

present and thereby avoid any loss of arsenious acid

by volatilization. Allow to cool and dilute with cold

water, then add about 50 per cent of the volume of

alcohol to insure complete precipitation of all lead as

lead sulphate. Filter and wash, boil filtrate to expel

alcohol, and add about 10 to 15 c.c. of hydrochloricacid. Precipitate the warm solution with hydrogen

sulphide. Filter and wash with dilute hydrogen sul-

phide water. All arsenic, antimony, and copper are

on the filter as sulphides. Test filtrate with hydrogen

sulphide as check on precipitation.

244. Dissolve the sulphides in caustic potash solu-

tion, then bring to a boil and pass hydrogen sulphide

into warm solution as before. Filter and test filtrate.

Wash with dilute ammonium sulphide solution. All

arsenic and antimony are in filtrate and any copper

present is on the filter. If any copper is present,

dissolve and titrate by the iodide method.

245. Make filtrate acid with hydrochloric acid and

add about 10 c.c. excess and pass in hydrogen sulphide

gas as before. Filter off the sulphides of arsenic and

antimony and wash with hydrogen sulphide water.


Dissolve these sulphides in about 10 c.c. aqua regia,

then dilute with water and make alkaline with ammo-

nia, adding about 25 c.c. excess. Then add from 1

to 2 grams tartaric acid and 10 to 15 c.c. magnesiamixture. Allow to stand over night. All the arsenic

is precipitated as ammonium magnesium arsenate.

Antimony remains in solution, being held there by the

tartaric acid present. Filter off the ammonium mag-nesium arsenate, washing with cold water containinga little ammonia, then dry, ignite, and weigh as mag-nesium pyroarsenate.

246. Acidify the filtrate with hydrochloric acid and

precipitate the antimony with hydrogen sulphide as

before; filter and wash with hydrogen sulphide water.

Separate the antimony sulphide from the filter paperand dissolve the adhering particles with ammoniumsulphide, transferring to a beaker. Wash with ammo-nia and evaporate to dryness on water bath. Carefullyadd a few drops of nitric acid and 1 to 2 c.c. of fum-

ing nitric acid to oxidize the antimony. Evaporate to

small bulk for crucible, and heat to dryness in water

bath, ignite at low red heat to constant weight.

247. Method II. Treat 10 grams of pigment in a No.

3-A casserole with about 10 grams potassium bisul-

phate, 10 c.c. nitric acid, 15 c.c. sulphuric acid, andabout 0.5 gram tartaric acid. Run to strong fumes;continue heating until all the carbon is destroyed andthe solution is clear. Cool, dilute, and boil until sol-

uble sulphates are in solution. Cool, filter, and wash

thoroughly. Add tartaric acid and pass hydrogen sul-

phide gas. Filter off arsenic and antimony sulphides.

Dissolve precipitate in potassium hydroxide solution

and filter. Pour filtrate into solution of hydrochloric

acid (2 to 1). Pass hydrogen sulphide gas and filter


off As2S3 on a weighed Gooch crucible. Wash with

alcohol and carbon bisulphide to remove sulphur.

248. Neutralize filtrate until Sb2S 3 begins to precipi-

tate. Dilute with equal volume of water, pass hydro-

gen sulphide gas, and filter off precipitate, Sb2S 3 ,on a

weighed Gooch crucible. Wash with alcohol and car-

bon bisulphide to remove sulphur. Dry and weigh.

249. ANALYSES OF LEADED ZINCS BY THE AUTHOR.I. II. in.

Moisture 0.03 0.02 0.04Sulphur dioxide 0.30 0.29 0.50Zinc sulphate . 86 1 . 49 1 . 26Lead sulphate 26.46 19.76 23.06Zincoxide 72.11 78.11 74.72Undetermined 0.24 0.33 0.42

100.00 100.00 100.00

I. II. in. IV.

Moisture 0.29 0.58 0.20 0.26Sulphur dioxide 0.01 0.01 0.01 0.01Arsenious oxide 0.68 0.47 0.32 1.60

Antimony oxide . 20 . 33 . 20 . 88Silica 0.14 0.05 0.04Zinc sulphate 0.78 0.55 1.61 0.84Lead sulphate 46.00 48.80 46.66 49.82Zincoxide 51.70 49.15 50.90 46.48Undetermined . 0.20 0.11 0.05 0.07

100.00 100.00 100.00 100.00

250. Moisture. Analysis of lithopone, ponolith, etc.

Heat 2 grams at 105 C. for 3 hours. Loss in weight

represents hygroscopic moisture.

251. Barium sulphate. To 1 gram add 10 c.c. of hy-drochloric acid and 10 c.c. of water, heat gently until

excess of acid has been expelled, dilute with 100 c.c. of

water, and boil gently for 10 minutes. Filter, ignite

and weigh residue as barium sulphate.

252. Total zinc. Neutralize the filtrate from the

barium sulphate with ammonia, make distinctly acid

with hydrochloric acid, heat to about 80 C., and titrate


with standard potassium ferrocyanide as described in

Chapter. XVI.

253. Zinc sulphide. Fuse 1 gram in a larger crucible

with a mixture of potassium nitrate and potassiumchlorate for about half an hour. Dissolve the fused

mass in dilute hydrochloric acid and boil the solution

with a strong nitric acid for half an hour. Filter off

the insoluble residue, precipitate the combined sul-

phuric acid in the filtrate with barium chloride in the

usual manner, filter, ignite, and weigh.

Wt. barium sulphate X 0.1373 = wt. sulphur.

Calculate sulphur to zinc sulphide.

254. Zinc oxide. Calculate excess of zinc over whatis required to form the zinc sulphide to zinc oxide.

255. Calcium. Occasionally zinc sulphide whites are

found on the market in which the barium sulphate has

been wholly or partially replaced with calcium sulphate.

In which case the calcium is estimated in the usual man-

ner, after the removal of the zinc as sulphide, and the

sulphuric acid combined with the calcium determined

as usual. The sulphuric acid due to the calcium mustbe deducted from the total sulphuric acid obtained byoxidation before calculating to zinc sulphide.

256. ANALYSES OF ZINC SULPHIDE WHITES BY AUTHOR.I. II.

Lithopone. Ponolith.

Moisture 0.20 0.18Barium sulphate 69.62 69.19Zinc sulphide 28.05 28.07Zinc oxide 1 . 55 2 . 27Undetermined . 0.58 0.29

100.00 100.00

CHAPTER XIV.

DETERMINATION OF FINENESS, COVERING POWER ANDTINTING STRENGTH OF PIGMENTS.

257. Determination of the comparative fineness of pig-

ments. The comparative fineness, or perhaps better,

the rate of settling of pigments, may be determined bymeans of the following apparatus:A is an ordinary graduated cylinder holding 100 c.c.

B is a black metal shield attached to the block D,which half surrounds the cylinder, and is provided with

a round opening T\ of an inch in diameter, exactly

opposite the 25 c.c. graduation.

C is an electric light.

258. The cylinder is filled to the 100 c.c. mark with

87 degrees gasoline; 2 grams of the pigment to be tested

are introduced, the cylinder stoppered, shaken 25 times

with a uniform motion, and the stop watch started with

the last shake. The cylinder is placed in position and

the time noted until the outlines of the aperature can

be plainly observed. This gives an excellent methodof determining the comparative fineness of pigments of

the same type.

259. Comparison of paints for covering power. The

following method described by G. W. Thompson,though open to criticism, furnishes in many cases

much valuable data:

"Use white pine boards, 30 inches long by 10 inches

wide, and approximately 1 inch thick. Each end of

the board is provided with a cleat having a tongue

fitting into a groove on the end of the board and124

FINENESS, COVERING POWER, TINTING STRENGTH. 125

securely nailed on. The entire board, including the

cleats, to be finished to the size given above. Three

of these boards may be primed with, say, the follow-

ing paint mixture:

White lead paste 100 Ibs.

Linseed oil, | boiled 75 Ibs.

No attempt is made to secure a definite amount of

priming paint to the unit of surface; this, for the

FIG. 6.

reason that the boards may vary considerably in their

absorptive power. When this priming coat is dry,

each board receives a diagonal stripe of lampblack in

japan about 1 inch wide on one or both sides of the

board, as may be desired. When this black stripe is

dry it is given a second coat of paint mixed to a consis-

tency proper for painting, the formula being recorded.

260. "The weight per gallon of the paint so mixed is

then obtained by finding its specific gravity and mul-

tiplying by 8.33, which gives the weight per gallon.


Inasmuch as the board used has a total surface of 680

square inches, all that is required to be done is to find

what the ratio is between 680 square inches and the

spreading rate at which it is desired to apply the paint

in order to find the fraction of the gallon to be applied

to each board. If the rate adopted is 120Q. square feet

to the gallon, then we get the formula:

680 sq. inches : 1200 sq. feet : : 1 . . x,

the reciprocal of V being the fraction of a gallon of

paint to be applied to each board, one coat. Havingthe weight of the paint per gallon we easily get the

amount of paint by weight to apply to each board, one

coat on all sides. When this second coat of paint is

thoroughly dry, a similar coat is applied; and, when

dry, the boards can be compared for the covering

power of the paints on them. We mention the paint-

ing of three boards with each paint to be compared.The purpose of this is that variations in results are

obtained between boards which are apparently painted

in an identical manner. These variations are not

great, but it is thought best to eliminate them, to a

certain extent, by painting three boards and selecting

the one giving medium results for comparison with

boards painted with other paints."

261. Determination of the tinting strength of colors.

The determination of the tinting strength of color pig-

ments is a very necessary operation in the valuation

and use of color pigments. The colors should always

be compared with a carefully selected standard.

262. Chrome yellows, ochres and greens. Weigh out

0.05 gram of color, place on a large glass plate, add 12

drops of bleached linseed oil, and rub up with a flat-

bottomed glass pestle or muller, then add 1 gram of

FINENESS, COVERING POWER, TINTING STRENGTH. 127

zinc oxide, kept solely for this purpose, and grind with

a circular motion fifty times, gather up with a sharp-

edged spatula and grind out twice more in like manner,giving the pestle a uniform pressure.

Weigh out 0.05 gram of the color kept as the standard,and treat in exactly the same manner as described

above. Transfer the standard to a microscope slide

and spread out evenly, drawing the spatula in one

direction only, and that toward the end of the slide.

In like manner transfer the prepared sample to the

slide, spread out evenly as before, drawing the spatula

in the same direction as directed above, and bringing

the edge of sample carefully to the edge of the stand-

ard. Compare the tints as shown on both sides of the

glass.

263. Reds, red oxides, etc. Use 0.02 gram of sampleto one gram of zinc oxide.

264. Blues and blacks. Use 0.01 gram of sample to

2 grams of zinc oxide with 24 drops of oil.

265. Paste goods. For testing the strength of paste

goods a can containing pure zinc oxide ground in

bleached linseed oil should be kept on hand.

266. Chrome yellows, ochres and greens. Use 0.5 gramof sample to 10 grams of zinc paste. Weigh accurately

on balanced glasses and grind as described above.

267. Reds, red oxides, etc. Use 0.2 gram of sample to

10 grams of zinc oxide paste.

268. Blues and blacks. Use 0.05 gram sample to 10

grams of zinc oxide paste.


209. GRAVITY AND VOLUME OF PIGMENTS.1

Drugs, Oils and Paints, Vol. XXI, page 299.

CHAPTER XV.

THE PRACTICAL TESTING OUT OF PAINTS.

270. Paints should be tested out by the chemist. The

chemical analysis of a can of paint will tell much re-

garding the value of that paint, but a thorough prac-

tical testing out on a suitable surface will tell more,

and the two in conjunction should render the chemist's

report complete and above question. Often, however,

the testing out is done by a so-called"practical man"

who has little or no knowledge of chemistry, and his

report for that very reason is apt to be misleading to

the chemist. In order to secure the most desirable

results, the chemist should do his own testing out, and

this involves a practical painting knowlege that can be

gained only by experience and under the guidance of

an able master painter.

271. Equipment. The chemist, if he is to do his own

testing out, should provide himself with an ample

equipment so that he may carry on his work unham-

pered. He should have mixing cans large enough to

hold sufficient paint for the coat to be applied and to

allow stirring without danger of slopping over the side.

A number of flat paddles of suitable sizes, a set of

measures and a strainer, are also essential articles.

All paint from the priming to the finishing coat should

be strained, as it assists in securing a more uniform

mixture than can be obtained by stirring. This is

especially necessary where tints are to be tried out.

272. The chemist should be provided with a good set

of brushes. It is a serious mistake to work with too

129


few brushes. For ordinary testing, the author believes

that oval brushes should be used, and never a large flat

brush which simply mops the paint on and does not

assist it in penetrating into the fibres of the wood.

An oval brush, being necessarily stiffer, rubs the oil

and pigment into the wood, thoroughly satisfying it.

For trimming and finishing the edges, a good chiseled

varnish brush can be used with advantage. Having

provided himself with a good set of brushes, the paint

chemist should take good care of them. New brushes

should never be placed in water. At the close of the

day's work they may be laid out full of paint on a

board, but should not be left this way for more than

twenty-four hours. When through with the brushes for

a time, they should be laid in a regular paint trough,

containing raw oil, or they may be suspended in a can

of raw oil containing a little turpentine, to prevent the

oil from becoming fatty. They should not be allowed

to stand on end, as it turns the painting edge of the

brush. Neither should brushes be allowed to remain

for long intervals in cans of paint. Brushes should

never be allowed to get"lousy" through the paint

drying on the bristles. In use, the brush should be

handled in such a manner as to wear the bristles to a

chisel edge-like point, and should never be jabbed into

corners, but carefully worked in.

273. The requisites for a paint. The requisites for a

high-grade paint are :

a. Covering power.6. Spreading capacity.

c. Durability.

d. Wearing evenly.

e. Failing by gradual wear, and

/. Leaving a good surface for repainting.

THE PRACTICAL TESTING OUT OF PAINTS. 131

In order to test out a paint to determine to what de-

gree it will fulfill the above requirements, the chemist

must have a clear understanding of the practical appli-

cation of paint and the suitability of different surfaces

to receive paint of varying consistencies.

274. Relation of the surface to the paint. The surface

on which the paint is to be tested out is of prime im-

portance, as it vitally affects the oil and turpentine

reduction which should be given the paint. If the sur-

face is a dense close-grained wood, a much more liberal

turpentine reduction must be used than when the sur-

face is more porous, as in the case of soft pine. Thelumber used should be well seasoned and entirely free

from dampness; and for outside paints, the surface

should be exposed to the direct rays of the sun for at

least a couple of days before applying the paint, even

if the surface is apparently free from moisture. If the

test is to be applied on a new building, every precautionshould be taken that the lumber has dried out thor-

oughly after the plastering has been done. It must be

remembered that there are eighty to ninety gallons of

water in every hundred square yards of plaster, and if

the house is kept closed during the time the plaster is

drying, the moisture must pass through the clapboard

siding, over which the paint is to be spread, in order to

escape. This operation is much slower and takes a

great deal longer time for completion, than most paintmen believe. This is especially true if the house is

sheathed with one or more thicknesses of paper be-

tween the boarding and siding. If the tests are to be

placed on small test frames, such as are described

below, or on specially constructed test fences, the con-

ditions affecting the application of the paint can be

more easily controlled.


275. Test structures. A convenient, practical, and

efficient method of conducting exposure tests is shownin the illustration at the beginning of this book, which

represents the first .of a series of tests which are beingconducted by the North Dakota Government Experi-ment Station.

This structure is 75 feet in length, 6 feet 6 inches high,

begins 15 inches from the ground, and faces east and

west. The posts are 5 feet apart and bedded in con-

crete. One side of the structure is plain boarded, the

other side clapboarded, the top capped, and the ends

boxed in a suitable manner. Four kinds of lumber

were used in the construction, representing four of the

most common varieties used for house building, and

were securely nailed to studding set 1 foot and 8 inches

apart. The structure was divided off into sections 16

inches wide and 5 feet in length, giving sufficient sur-

face for the careful brushing out of the paint ;each type

of paint being applied over the four kinds of wood, and

the work being three coats in each case. Twenty-onemixed paints and white leads were applied on this

fence, representing prevailing types of combinations.

Figure 7 represents a second series of exposure tests

begun during the summer of 1907. These fences are

like the one described above, except that they are each

100 feet in length. There is a four-inch air space be-

tween the two surfaces of each fence, the numerous

crevices between the boards permit of free circulation

of air, and insure the prevention of continued damp-ness on the inside of the structure. Figure 8 illustrates

the framework to which the boards and siding were

nailed.

276. A more convenient method for making exposure

tests, the painting of which may be done in the


laboratory, is illustrated in Fig. 9. These test frames,

so-called, have the additional merit of being easily trans-

ported from one place to another for inspection. These

frames are 3 feet in length and 16 inches in width, the

edge of the upper clapboard projecting half an inch

above the cleats, arid the lower clapboard set out a

FIG. 9. PORTABLE TEST FRAMES.

little, so that two or more frames may be put together,

forming a unit surface exactly similar to the side of

a house. These frames are made to be screwed to a

framework like that illustrated in Fig. 8. The clap-

boards, four in number, are set four inches to the

weather and are of two kinds of wood. The arrange-ment of the back cleats a, a, a and the end strips b, b

through which the screws are inserted to hold the


frame to the skeleton fence, are clearly shown in the

illustrations.

These end strips serve a much more important pur-

pose, and one which makes the tests much more valu-

able than on a plain board surface, in that it tests out

the brushing qualities of the paint very thoroughly. Apoor paint will often brush out satisfactorily on an

ordinary flat section of board, but will at once show its

inferior quality when the painter attempts to work it

into the corners and brush it away from the end strips,

on the clapboard surface. In fact, it closely reproduces

the actual conditions which the painter would encounter

in applying the paint on an average house.

277. Application of the priming coat. In order to secure

the best results with any given paint, three coats should

be applied; of these three the most important is the

priming coat. It compares with the foundation of a

house, which, if not solidly and firmly constructed, ren-

ders the whole superstructure unstable. The priming

coat, if not bedded thoroughly in the wood, will not

serve to anchor and firmly bind the two additional

coats to the surface. The essential consideration with

the priming or first coat is to secure suitable penetra-

tion into the wood. In other words, the wood must be

thoroughly satisfied. The necessity of this is explained

with great force and clearness by J. B. Campbell, in

his work entitled"Practical Painting."

278. The paint to be tested out, if of the ready mixed

type, should be thoroughly" broken up," first pouring

off the oil portion, stirring the residue until free from

lumps, and then gradually working the oil portion back

into the paste. This is best accomplished by removing

the entire contents of the can into a larger mixing can,

kept solely for this purpose. The consistency of the


paint after being" broken up

"should be carefully noted,

whether it is thin, medium, or heavy, as the amount of

reduction which the paint will stand depends largely on

its consistency.

279. Raw linseed oil should almost without exception

be used instead of boiled oil for reducing the paint for

the priming coat. Raw oil dries slowly and from the

bottom up, which allows it to be thoroughly absorbed

and to harden uniformly. Boiled oil does not penetrate

the wood, owing to its rapid drying qualities, and hence

the coating formed is a surface coating only, and does

not become firmly anchored to the wood. Turpentineshould be used liberally in the priming coat, as, by re-

ducing the specific gravity and rendering the oil more

mobile, it assists it in penetrating into the deeper

pores of the wood, thus securing increased penetrationand also more rapid drying. The harder and closer

grained the wood, the larger the amount of turpentine

required.

280. The following oil and turpentine reductions 1 will

enable the chemist to judge the reduction required in

most cases.

281. Oil reductions."A full oil reduction consists of

oil only, with the exception of 7V gallon of turpentineto the gallon of paint, to assist in penetration; this is not

enough turpentine to destroy the luster of the paint,

and will accomplish the purpose of penetrating a hard

or glossy surface where it would be unsatisfactory -to

apply paint without the addition of a small percentageof this thinner."

282. "A liberal oil reduction consists of seven eighth

oil and one eighth turpentine to form the total amountof reducers; this amount of turpentine will cause more

1Campbell, Practical Painting, p. 63.


rapid and even penetration, but will not destroy the

luster of heavy-bodied paint."

283. "A medium oil reduction consists of three

fourths oil and one fourth turpentine to form the total

amount of reducers; this amount of turpentine will

destroy part of the luster and cause deep penetration

on a hard surface."

284. Turpentine reductions." A full turpentine reduc-

tion consists of nothing but turpentine, and is used for

producing a flat paint."

285. "A liberal turpentine reduction consists of seven

eighths turpentine and one eighth oil, to form the total

amount of reducers."

286. "A medium turpentine reduction is half tur-

pentine and half oil."

287. "Dark shades require more turpentine to pro-

duce the same results, as to penetration and flattening

the paint, than light shades. Zinc and combination

paints require more turpentine than strictly pure lead to

produce the same results, as to destroying the luster of

the paint. Where light shades require f gallon of tur-

pentine to produce the desired results as to flattening

or destroying the luster and securing penetration, dark

shades require T\ of a gallon to produce like results."

288. It is also well to remember in making the reduc-

tion that turpentine reduces twice as fast as raw oil.

The consistency to which the paint should be reduced

for priming must necessarily be left to the judgment of

the person applying it, and hence no definite directions

can be given, but the following directions given byCampbell

1 have been found very helpful by the author.

289. "In priming soft wood, the paint should be ap-

plied with a full brush, and enough paint used at all

1 Practical Painting, p. 69.


times to satisfy the surface. It should be well brushed,

and especially on the harder grain, to assist or force the

paint into this close grain, and remove by hard brush-

ing any surplus paint that remains on the surface. Onhard or close-grained wood a medium full brush should

be used in applying the paint, as this class of wooddoes not possess the absorbing properties of softer

woods, but requires more brushing in order to force a

sufficient amount of oil and binder into the wood and

at the same time not leave an excess of paint on the

surface."

290. "If the priming coat is of the proper consistency,

carrying sufficient pigment to fill and hide the grain, and

well brushed into the wood, most of the absorption will

have ceased with this coat and no excess of pigment be

left on the surface. This thin coat will allow the second

coat to penetrate through and satisfy any part of the

wood which was not fully filled at the time of priming,and also allow the second coat to bind itself to the woodand priming coat."

291. Application of the middle coat. The priming coat

should be given ample time to dry before applying the

second coat, which, as Mr. Campbell states with much

truth, should be "considered the medium between the

foundation coat and the protecting or finishing coat."

Careful judgment should be exercised in preparing the

paint for this coating. "It must not be too elastic, andshould dry firm without a high gloss. Too heavy an oil

reduction will leave a high, glossy surface, over which

the finishing coat will not adhere or properly dry."Sufficient turpentine should be used to secure the nec-

essary penetration into the priming coat and to "flat-

ten" out the paint so that it will show little or no gloss

after 48 to 72 hours. Over such a surface the finishing


coat can be applied evenly, smoothly, and with great

adherence. The directions for application as issued

by most paint manufacturers are apt to fall short in

the amount of turpentine necessary for the proper

application of the second coat.

292. Nail holes and cracks should be carefully put-

tied. Cheap putty should be avoided, as it is apt to

turn yellow and ultimately crumble and fall out. It

is often better for the paint chemist to make his own

putty, using medium whiting, raw oil, and paste white

lead to about 20 per cent of the whiting used. The

mixture should be carefully kneaded and worked until

of stiff consistency.

293. If the work is to be only two-coat, the paint

should have a full oil reduction, so as to insure suffi-

cient elasticity and opacity, and should be worked out

well under the brush.

294. Application of third coat. The paint for this

coat should be of good consistency, with a full raw-oil

reduction, so that it may be brushed out smoothly and

evenly, and be sufficiently elastic so as to withstand

severe exposures. Too much importance cannot be

placed on the thorough brushing of the paint, as the

durability and protection it affords are dependent to a

great extent upon the thoroughness with which this is

done. Paint flowed on will soon crack and come off,

while, if plenty of muscle is used, it will make the finish-

ing coat adhere more firmly to the second coat.

295. Application of paste leads and paste paints. In

testing out paste paints and leads some convenient

method should be adopted for calculating the amount

of oil used in gallons per hundred pounds of paste. One

of the simplest schemes is to weigh out the leads or

pastes in 12| oz. quantities or multiples thereof. Then


each ounce of oil used is equivalent to one gallon perhundred pounds of paste.

One gallon is equivalent to 128 oz.

One hundred pounds are equivalent to 1600 oz.

1600 -5- 128 = 12.5

In this way the necessary quantities of turpentine and

drier can be rapidly calculated and measured out. For

instance, if a specification to be tested out read,

100 Ibs. white lead,

7 gal. raw linseed oil,

\ gal. turpentine,

| gal. turpentine drier,

the above scheme would call for

12J oz. White lead,

7 oz. raw linseed oil,

\ oz. turpentine,

\ oz. turpentine drier.

If larger amounts were required, the necessary mul-

tiple of 12| should be used and the other figures in-

creased accordingly.

296. Driers. The proper use of driers is often a per-

plexing problem with the paint chemist. Campbell l

says: "A wide experience with the products as used bythe painter shows the greatest possible difference be-

.tween them. Some of them are sufficiently powerfulso that even 5 per cent added to raw oil is enough to

cause it to dry as fast as with boiled oil, and not only

that, but to dry throughout or from the bottom up, and

not merely surface dry, as will boiled oil. Others again

are so loaded with rosin and petroleum products and

so deficient in true drying properties that 25 per cent or

1 Practical Painting, p. 66.


more is required to accomplish this result, and then the

resulting surface will be spongy or brittle, as the case

may be, but in any event lacking in durability." In

the face of these conditions the only recourse left the

chemist is to test out his driers thoroughly, as described

in a later chapter."

297. "The Japan or drier should be mixed with the

paint while it is in semipaste form. The mixing is

thus uniform and the results satisfactory. If an at-

tempt is made to add it after the paint is ready for the

brush, the Japan is liable to curdle; it will be difficult

to mix uniformly and the resulting work is liable to be

spotted, drying flat in some places and glossy in others."

It should be borne in mind that paints containing zinc

or dark colors will require more Japan than white lead

alone, provided that it is essential to dry in a given

time.

CHAPTER XVI.

ANALYSIS OF WHITE PAINTS.

298. Qualitative analysis. In the majority of cases a

complete qualitative analysis of the pigments presentis hardly worth the time it requires, as there is but

little time lost in following the regular quantitativescheme. If, however, a qualitative analysis is desired,

the following outline will be found sufficient in most

instances, the removal of the vehicle previous to these

tests being understood.

299. Carbonates. Effervescence with concentrated

hydrochloric acid indicates carbonates, or hydrogen

sulphide if zinc sulphide be present, the latter being

distinguished by its odor and by the fumes blackeninga piece of filter paper moistened with lead acetate.

300. Barytes, silica, clay, or other silicates. Boil above

mixture five minutes, dilute with boiling water, filter.

An insoluble residue may be barytes, silica, clay, or

other silicates. Test for barytes with flame test, usinga platinum wire. A characteristic green color indicates

barium.

301. Sulphates. Test a small portion of the acid fil-

trate for combined sulphuric acid with a few drops of

barium chloride.

302. Lead. Test another small portion of the acid fil-

trate with sulphuric acid. A white precipitate at once,

or on standing indicates lead.

303. Zinc. Take another small portion of the acid fil-

trate and add a few drops of potassium ferrocyanide.

A white precipitate with a bluish tinge indicates zinc.

143


304. Calcium. The remaining portion of the acid ni-

trate is made alkaline with ammonia and hydrogen sul-

phide passed in for five minutes. Filter and test filtrate

for calcium with ammonium oxalate, setting aside in a

warm place.

305. Magnesium. After completely precipitating the

calcium add a few drops of hydrogen sodium phosphate.A precipitate on standing indicates the presence of mag-nesium compounds.The identification of the forms in which the lead

may occur can only be determined by the quantitative

scheme if both sulphates and carbonates are present.

Quantitative Analysis of White Paints.

306. Total lead. Weigh 1 gram of the dry pigment into

a 250 c.c. beaker. Add 30 c.c. of strong hydrochloric

acid, boil 5 minutes, add 50 c.c. of hot water, heat 15

minutes longer, settle, filter while hot, and wash thor-

oughly with boiling water. The washing should be

begun the instant the solution has filtered through, in

order to avoid any crystallization of lead chloride in

the pores of the filter paper. Once formed the crystals

can only be dissolved with difficulty and with the use

of an excess of wash water, which, as stated, must be

at boiling temperature. - This operation is best con-

ducted by the aid of suction. Casein and other prod-

ucts of a similar nature are occasionally used in the

manufacture of mixed paints in considerable quantities,

and the analyst should always be on the lookout for

the possible presence of these substances.

307. The solution is made just alkaline with ammo-

nia, then just acid to litmus with hydrochloric acid. It

is very necessary that the solution be only barely acid,

ANALYSIS OF WHITE PAINTS. 145

as a comparatively small quantity of free acid will keepconsiderable lead from precipitating. Having been"

made barely alkaline, which is indicated by the precip-

itation of the lead, the solution is brought to a faintly

acid condition by using dilute hydrochloric acid (1 to

10). Dilute to about 350 c.c. Cool, pass in hydrogen

sulphide gas, noting the color of the precipitate : if gray,

some zinc is being thrown down; if reddish black, the

solution is too acid. Add a few drops of dilute acid

or ammonia as the case requires. Settle, filter, and

wash with cold water.

308. Place filter and precipitate in 25 c.c. of nitric

acid and 25 c.c. of water, heat gently until the lead has

all dissolved, as shown by the residual sulphur having a

yellow to whitish color. Do not boil hard enough thor-

oughly to disintegrate the filter paper. If difficulty is

experienced in dissolving the lead contained in the sul-

phur particles, it is better to collect them into a ball

with the aid of a stirring rod and remove to a small

beaker and treat with a few cubic centimeters concen-

trated nitric acid, and heat until dissolved, then pourback into the larger beaker.

309. Pour solution and filter paper on to a suction

funnel provided with a platinum cone. If any fine

particles pass through, pour the filtrate back again.

This procedure permits the washing of the filter mass

with a very small amount of water, thus saving consid-

erable time in the subsequent evaporation. Add 5 c.c.

of dilute sulphuric acid to filtrate, and evaporate until

sulphur trioxide fumes appear. Cool, add 25 c.c. of

water, 25 c.c. of alcohol; allow to stand one-half hour

with occasional stirring; filter, using Gooch crucible,

wash with dilute alcohol, dry, heat gently over ordi-

nary lamp, and weigh as lead sulphate.


310. Calcium. The filtrate containing the zinc, cal-

cium, and possibly magnesium is made slightly alkaline

with ammonia, a few drops of a mercuric chloride solu-

tion (1 to 10) added, and a stream of hydrogen sulphide

gas passed into the solution for about ten minutes.

The addition of the mercuric chloride renders the

precipitate granular and very easy to filter, and en-

tirely obviates the difficulty of filtering a slimy zinc

sulphide precipitate. In the analysis of tints where the

zinc cannot be titrated until it has been freed from iron,

the addition of the mercuric chloride will not cause anytrouble, as treatment with hydrochloric acid results in

the solution of the zinc only, the mercuric sulphide

being insoluble in hydrochloric acid. Settle, decant,

filter, and wash.

311. Evaporate the filtrate from above precipitate to

about 150 c.c., make alkaline with ammonia, add ammo-nium oxalate (50 c.c. for 1 gram of lime), usually 20 c.c.

is sufficient, and set in a warm place for two or three

hours. Filter, wash, ignite, and weigh as calcium oxide,

or titrate precipitate with permanganate by placingfilter and the thoroughly washed precipitate in a 400

c.c. beaker, adding 200 c.c. of boiling water and 25 c.c.

of dilute sulphuric acid, and titrate with standard

tenth-normal potassium permanganate.

1 c.c. tenth-normal permanganate = 0.0028 gram CaO.

1 c.c. tenth-normal permanganate =0.0050 gram CaC0 3 .

Barium carbonate is still to be found in certain mixed

paints, and it is advisable to test for the presence of

soluble barium with a few drops of sulphuric acid

before precipitating the calcium.

312. Magnesium. The filtrate from the cajcium oxa-

late should be tested for magnesium by treating with


hydrogen sodium phosphate. Allow to stand one-half

hour, add 25 c.c. of ammonia, allow to stand one hour,

then filter on to a Gooch crucible, wash with dilute am-

monia, ignite, and weigh.

Weight precipitate X 0.7575 = weight magnesiumcarbonate.

313. Zinc oxide. Reagents. Standard zinc solution.

Dissolve 10 grams of chemically pure zinc in hydro-chloric acid in a graduated liter flask, add 50 grams of

ammonium chloride, and make up to 1 liter.

1 c.c. = 0.01 gram zinc or 0.01245 gram zinc oxide.

314. Standard potassium ferrocyanide solution. Dis-

solve 46 to 48 grams of crystallized potassium ferro-

cyanide in water, make to 1000 c.c.

315. Uranium nitrate solution. Dissolve 15 grams of

uranium nitrate in 100 c.c. of water.

316. Standardizing the ferrocyanide solution. To de-

termine the value of the potassium ferrocyanide solu-

tion, pipette 25 c.c. of the zinc solution into a 400 c.c.

beaker. Dilute somewhat and make faintly alkaline

with ammonia, bring to a faintly acid condition with

hydrochloric acid, and then add 3 c.c. excess of the con-

centrated acid, dilute to a total volume of about 250 c.c.,

heat to 80 C., and titrate as follows: Pour off about 10

c.c. of the zinc solution into a small beaker and set

aside, run the ferrocyanide into the remainder from a

'burette, a few cubic centimeters at a time, until the

solution takes on a slight ash-gray color, or until a dropof the solution placed in contact with a drop of the

uranium nitrate solution on a porcelain plate turns to a

distinct brownish color. Often the end point has been

passed by quite a little.

317. The 10 c.c. of zinc solution that has been re-

served is now added and the titration continued, drop


by drop, testing a drop of the solution carefully on the

porcelain plate after each addition of ferrocyanide solu-

tion. Some little time is required for the test drop to

change color, so that the end point may have been

passed slightly. This may be corrected for by makinga memorandum of the burette readings, having the

test drops arranged in regular order and taking as the

proper reading the one first showing a distinct brown-

ish tinge. Having noted the number of cubic centi-

meters of ferrocyanide required for the titration of the

standard zinc solution, the value of 1 c.c. may be readily

calculated.

318. Titration of sample. One-half gram of the sample,if high in zinc, or 1 gram, if the zinc content is fairly low,

or the zinc sulphide precipitate obtained in section 310,

is dissolved in a covered beaker in 10 c.c. of hydrochlo-

ric acid and 10 c.c. of water, the solution diluted and

treated exactly as described above for the standard zinc

solution, care being taken to titrate to exactly the same

depth of color on the porcelain test plate. If the method

is carefully carried out, the procedure being uniformlythe same in each determination, the results will be

found satisfactorily accurate.

319. Lead sulphate. Dissolve 0.5 gram in water, 25 c.c.

hydrochloric acid in light excess. Dilute to 200 c.c.

and add a piece of aluminum foil which about covers

the bottom of the beaker. It is important that this be

held at the bottom by a glass rod. Boil gently until

the lead is precipitated. Completion of this is shown

by the lead ceasing to coat or cling to the aluminum.

Decant through a filter, pressing the lead sponge into

a cake to free it from solution. Add to filtrate a little

sulphur-free bromine water, ignite, and weigh as ba-

rium sulphate. Calculate to lead sulphate by multi-


plying by 1.3 as a factor, unless calcium sulphate is

present, in which case it is advisable to make use of

Thompson's separation.

320. In the absence of barium sulphate the com-

bined sulphuric acid may be estimated by H. Mann-hardt's method : Grind 1 gram of pigment with 1 gramof sodium carbonate very intimately in an agate

mortar. Boil gently for ten minutes, the combined

sulphuric acid, and in the case of colors containing

chromates the chromic acid, will pass into solution and

may be estimated in the filtrate in the usual manner.

If necessary collect the insoluble portion on a filter,

dry, detach, and triturate a second time.

321. Basic carbonate of lead (white lead). After de-

ducting the amount of lead present in the pigment as

sulphate of lead, calculate the rest of the lead as white

lead by multiplying the remaining sulphate by 0.852,

unless sublimed lead is suspected to be present, in

which case the combined lead oxide must be taken into

consideration.

322. Insoluble residue. The insoluble residue from

the original hydrochloric acid treatment may contain

barytes, magnesium silicate, silica, and clay. Ignite

filter paper and residue until white, weigh as total in-

soluble matter; grind in agate mortar with about 10

times its weight of sodium carbonate, fuse for 1 hour

in a platinum crucible, and dissolve out in hot water.

323. Barium sulphate. The solution from the fusion

is filtered. The residue consists of barium carbonate,

magnesium carbonate, etc., and is washed with hot

water. The filtrate and washings are saved. Pierce

filter paper and wash precipitate into clean beaker with

hot dilute hydrochloric acid; finish washing with hot

water, heat to boiling, add 10 c.c. of dilute sulphuric


acid to precipitate barium, filter, ignite, and weigh as

barium sulphate.

324. Silica. The filtrate from the barium sulphate is

added with care to the filtrate reserved in the preceding

paragraph, making distinctly acid; evaporate to com-

plete dryness, cool, add 15 c.c. of hydrochloric acid,

heat to boiling, cool, settle, filter, ignite, and weigh as

silica.

325. Alumina. The filtrate from the silica will con-

tain all of the alumina except that which was dissolved

in the original treatment with hydrochloric acid. This

is quite constant, varying from .004 to .005 gram per

gram of clay. The acid filtrates are made slightly alka-

line with ammonia, and boil until odor disappears.

Settle, filter, wash, ignite, and weigh as alumina.

Weight alumina X 2.5372 = weight clay.

Weight clay X .4667 = weight of silica in clay.

Any difference greater than 5 per cent may be con-

sidered as free or added silica, according to Scott.

326. Calcium and Magnesium oxides. If qualitative

test shows presence of magnesium in insoluble residue

from the first hydrochloric acid treatment it was present

probably as magnesium silicate. Treat filtrate from the

aluminum hydroxide for calcium and magnesium oxides.

Magnesium silicate contains 3 to 5 per cent combined

water.

327. Hydrofluoric acid treatment. Instead of resorting

to fusion with sodium carbonate, the insoluble residue,

which should be weighed up in a clean platinum crucible,

may be treated with several drops of pure concen-

trated hydrofluoric acid and sulphuric acid and heated

gently on a sand bath under the hood, using onlysufficient heat slowly to volatilize the silica and sul-

phuric acid. Dissolve out in water acidulated with


hydrochloric acid. The residue, which is barium sul-

phate, is filtered off and estimated as such. The filtrate

will contain a,ny aluminum, calcium, and magnesium

present which may be estimated and calculated as

oxides as above described. The combined weight of

the barium sulphate, alumina, calcium, and magnesiumoxides subtracted from the weight of the insoluble

residue used gives the weight of silica. This operationis much shorter than resorting to a fusion and equallyas accurate.

328. Mixed carbonates and sulphates. Occasionally

paints are met with which contain calcium sulphate,

calcium carbonate, sulphate of lead, and white lead

(basic carbonate of lead), in which case it is necessaryto make a separation of the calcium compounds, which

may be effected by Thompson's method as follows:

To 1 gram of the sample are added 20 c.c. of a mix-

ture of nine parts alcohol (95 per cent) and one part of

concentrated nitric acid. Stir, and allow to stand 20

minutes. Decant on a filter and repeat the treatment

with the acid-alcohol mixture four times, allowing it to

stand each time before decanting. The calcium car-

bonate will go into solution, while the calcium sulphateor gypsum remains undissolved. Add filter and con-

tents to the residue remaining in the beaker; dissolve in

hydrochloric acid with sufficient water to insure the

solution of the calcium. Make alkaline with ammonia,

pass in hydrogen sulphide for 10 minutes, boil, settle,

filter. The filtrate and washings are concentrated to

about 150 c.c. and the calcium precipitated with am-monium oxalate in the usual manner. The ignited

precipitate is calculated to hydrated calcium sulphate.

329. Estimation of carbon dioxide in the presence of

zinc sulphide. This method, devised by Mannhardt, is


often useful in determining complex mixtures of pig-

ments. One gram of the pigment is ground for several

minutes in a smooth glass mortar with an excess of

bichromate of potash, using considerable pressure; the

mixture is then placed in the carbon dioxide generatorand the carbon dioxide liberated and estimated in the

usual manner.

330. Calculations. The ignited precipitate of calcium

oxide obtained from the portion insolable in the acid-

alcohol mixture is subtracted from the total calcium

weighed as oxide;the remaining calcium oxide is calcu-

lated to calcium carbonate. The total carbon dioxide

is determined in a portion of the sample, the portiondue to the calcium carbonate is deducted from the total

amount, and the remainder calculated to basic carbon-

ate of lead. The combined sulphuric acid due to the

sulphate of lime is deducted from the total combined

sulphuric acid, and the remainder calculated to sulphateof lead.

Wt. calcium oxide X 3.0715 = hydrated calcium sul-

phate.Wt. calcium oxide X 1.784 = calcium carbonate.

Wt. calcium carbonate X 0.440 = carbon dioxide.

Wt'. carbon dioxide X 8.8068 = basic carbonate of lead.

Wt. of hydrated sulphate of lime X 0.4561 = combined

sulphuric acid.

Wt. of combined sulphuric acid X 3.788 = sulphate of

lead.

CHAPTER XVII.

ANALYSIS OF WHITE PAINTS (continued).

Analysis of White Paints According to Thompson.1

331. Schemes for the separation of the constituents

from each other and into their proximate combinations

depend on the constituents present, and we can treat

this subject in no better way than by taking typical

cases, which we now do.

332. Sample 1 is a mixture of barytes, white lead, and

zinc oxide.

Two 1-gram portions are weighed out. One is dis-

solved in acetic acid and filtered, the insoluble matter

ignited and weighed as barytes, the lead in the soluble

portion precipitated with bichromate of potash, weighedin Gooch crucible as chromate, and calculated to white

lead.

The other portion is dissolved in dilute nitric acid,

sulphuric acid added in excess, evaporation carried to

fumes, water added, the zinc sulphate solution filtered

from barytes and lead sulphate and precipitated

directly as carbonate, filtered, ignited, and weighed as

oxide.

. 333. Sample 2 is a mixture of barytes and so-called

sublimed white lead.

Weigh out three 1-gram portions. In one determine

zinc oxide, as in case 1. Treat a second portion with

boiling acetic acid, filter, determine lead in filtrate, and

calculate to lead oxide. Treat third portion by boiling

1 J. Soc. Chem. Ind., June 30, 1896.

153


with acid ammonium acetate, filter, ignite, and weighresidue as barytes; determine total lead in nitrate,

deduct from it the lead as oxide, and calculate the

remainder to sulphate. Sublimed lead contains no

hydrate of lead, and its relative whiteness is probablydue to the oxide of lead being combined with the sul-

phate as basic sulphate. Its analysis should be re-

ported in terms of sulphate of lead, oxide of lead, and

oxide of zinc.

334. Sample 3 is a mixture of barytes, sublimed lead,

and white lead.

Determine barytes, zinc oxide, lead soluble in

acetic acid and in ammonium acetate, as in case 2;

also, determine carbonic acid, which calculate to white

lead, deduct lead in white lead from the lead soluble

in acetic acid, and calculate the remainder to lead

oxide.

335. Sample 4 is a mixture of barytes, white lead, and

carbonate of lime.

Determine barytes and lead soluble in acetic acid

(white lead), as in case 1. In filtrate from lead chro-

mate precipitate lime as oxalate, weigh as sulphate, and

calculate to carbonate. Chromic acid does not inter-

fere with the precipitation of lime as oxalate from

acetic acid solution.

336. Sample 5 is a mixture of barytes, white lead,

zinc oxide, and carbonate of lime.

Determine barytes and white lead as in case 1. Dis-

solve another portion in acetic acid, filter, and pass sul-

phureted hydrogen through the boiling solution, filter,

and precipitate lime in filtrate as oxalate; dissolve

mixed sulphides of lead and zinc in dilute nitric acid,

evaporate to fumes with sulphuric acid, separate, and

determine zinc oxide, as in case 1.


337. Sample 6 is a mixture of barytes, white lead,

sublimed lead, and carbonate of lime.

Determine barytes, lead soluble in acetic acid and in

ammonium acetate, as in case 2, lime and zinc oxide, as

in case 5, and carbonic acid. Calculate lime to car-

bonate of lime, deduct carbonic acid in it from total

carbonic acid, calculate the remainder of it to white

lead, deduct lead in white lead from lead soluble in

acetic acid, and calculate the remainder to oxide of

lead.

338. Sample 7 contains as insoluble matter, barytes,

china clay, and silica.

After igniting and weighing the insoluble matter,

carbonate of soda is added to it and the mixture

fused. The fused mass is treated with water and the

insoluble portion filtered off and washed. This insolu-

ble portion is dissolved in dilute hydrochloric acid,

and the barium present precipitated with sulphuric

acid in excess. The barium sulphate is filtered out,

ignited, weighed, and if this weight does not differ

materially say by 2 per cent from the weight of

the total insoluble matter, the total insoluble matter

is reported as barytes. If the difference is greater

than this, add the filtrate from the barium sulphate

precipitate to the water-soluble portion of fusion.

Evaporate and determine the silica and the alumina

in the regular way. Calculate the alumina to china

clay on the arbitrary formula 2 Si02 ,A12O 3 ,

2 H2O,

and deduct the silica in it from the silica, reporting

the latter in a free state. It is to be borne in mindthat china clay gives a loss of about 13 per cent on

ignition, which must be allowed for. China clay is

but slightly used in white paints as compared with

barytes and silica.


339. Sample 9 contains sulphide of zinc.

Samples of this character are usually mixtures in

varying proportions of barium sulphate, sulphide of

zinc, and oxide of zinc. Determine barytes as matter

insoluble in nitric acid, the total zinc, as in case 1,

and the zinc soluble 'in acetic acid, which is oxide

of zinc. Calculate the zinc insoluble in acetic acid to

sulphide.

340. Sample 10 contains sulphite of lead.

This is of rare occurrence. Sulphite of lead is insol-

uble in ammonium acetate, and may be filtered out

and weighed as such. It is apt on exposure to the air

in the moist state to become oxidized to sulphate of

lead.

There are certain arbitrary positions which the

chemist must take in reporting analyses of white

paints :

1st. White lead is not uniformly of the composition

usually given as theoretical (2 PbCO 3), (PbH2O2), but

in reporting we must accept this as the basis of calcu-

lating results, unless it is demonstrated that the com-

position of the white lead is very abnormal.

2d. In reporting oxide of lead present this should

not be done except in the presence of sulphate of lead,

and if white lead is present, then only where the oxide

is more than 1 per cent;otherwise calculate all the lead

soluble in acetic acid to white lead.

3d. China clay is to be calculated to the arbitrary

formula given.

In outlining the above methods we have in mind

many samples that we have analyzed, and the combi-

nations we have chosen are those we have actually

found present.


341. TYPICAL ANALYSES OF MIXED PAINTS. 1

I. II. III. IV.

Color Stone. Lead Gray. White.

Can l.OOqt. 4.06 qt. 1.06qt. l.OSqt.Contents ,90 qt. 4.01 qt. 1.05qt. .93 qt.Net weight .... 2 Ibs. 14 oz. 16 Ibs. 3 oz. 4 Ibs. 3 Ibs. 4 oz.

Vehicle 50.1 34.2 38.2 36.9

Pigment 49.9 65.8 61.8 63.1

100.00 100.00 100.00 100.00

ANALYSIS OF VEHICLE.

Linseed oil .... 68.9 90.4 90.6 89.6Benzine drier . . . 16.1 3.4 10.1

Turpentine drier 9.4 4.0Water . . 15.0 0.2 2.0

, 0.3

White lead . . .

Lead sulphateZinc oxide . . .

Calcium carbonate

Barytes ....Silica

100.00 100.00 100.00 100.00

ANALYSIS OF PIGMENT.21.73 49.53 16.64 21.560.85 0.44 13.48 1.09

47.89 49.64 39.80 49.2521.98 10.68 1.80

18.935.41

Magnesium silicate, 25 . 87Color, undeter-

mined, etc. . . . 2.14 0.39 0.47 0.43

100.00 100.00 100.00 100.00

1Analyses made by author.

342. No. I is a fair type of a large number of mixed

paints, short in volume, short in weight, low in pigment,

nearly one-third of the vehicle being benzine and water,

and ,27 per cent of total pigment inert material.

No. II is a strictly first-class paint in every respect, full

measure, 16 Ibs. to the gallon, pure turpentine drier, and

high white lead content.

No. Ill is full measure and full weight. The percent-

age of drier is well within the usually accepted limits,

but the manufacturer obtains a considerable relief bythe use of nearly 30 per cent of inert pigments costing


only a small fraction of the price of white lead or zinc.

This paint also has a very small percentage of addedwater.

No. IV is 7 per cent short in volume, is low in lead pig-

ments, and contains nearly 28 per cent of inert pigment,which in this case is mainly magnesium silicate.

343. Calculation of the approximate cost of mixed

paints using No. I and No, II as types.

COST OF VEHICLE.

100 gallons (750 pounds), No. I, cost $32.81.

1 pound costs $0.0438.

50 . 1 pounds cost $2 . 19.

100 gallons (750 pounds), No. II, cost $45. 56.


34. 2 pounds cost $2.09.

COST OF PIGMENT.

Lead sulphate present in *he zinc oxide.


100 pounds total pigment, No. I, cost $4.22.


49.9 pounds cost $2.11.

100 pounds total pigment, No. II, cost $5 . 74.

1 pound costs $0 . 057.

65 . 8 pounds cost $3.75.

No. I.

50 . 1 pounds liquid cost $2 . 1949 . 9 pounds pigment cost 2.11

100 . pounds paint cost $4 . 301 . pound paint costs . 0431 gallon (2 pounds 14 ounces) X 4 costs . . 0.495

No. II.

34 . 2 pounds liquid cost $2 . 0965.8 pounds pigment cost 3.75

100 . pounds paint cost .......... $5 . 841 pound paint costs . ......... . 05841 gallon (or 16 pounds 3 ounces) costs . . . 945

In other words, one paint costs almost exactly twice

as much as the other, as regards paint and oil ingredi-

ents. The cost of the can (gallon size), label, and crate

is about 10 cents. Salesmen's commissions, salary,

and traveling expenses are about 5 cents per gallon;

the cost of manufacture, depreciation of plant and

machinery, 6 to 8 cents per gallon.

It must also be borne in mind that the cost of crude

materials has advanced markedly during the last few

years. The following table prepared by the Paint

Manufacturers' Association shows the increase in cost

of "various paint materials in 1907 as compared with

1897:

White lead ................. 61.8Zinc oxide ................. 40 . 5Barium sulphate............... 44.2Linseed oil ................ . 45 . 4

Turpentine ................. 155.0Japan drier ....... ........... 42.0Tin cans ...... . ........... 33.0

Packing boxes . , 50* ........... 64 . 2


344. ANALYSES OF SUBLIMED LEAD PAINTS BY AUTHOR.

1 Benzine.

100.00 10000 100.00

2 Sublimed lead.

100.00

In the above analyses the percentage of zinc oxide

incidental to the manufacture of sublimed lead is in-

cluded in the total zinc oxide.

345. ANALYSES OF LEADED ZINC PAINTS BY AUTHOR.

100.0 100.0 100.0 100.0


ANALYSIS OF VEHICLE.

Linseed oil .

Benzine drier

Water

80.28.511.3

100.0

56.920.622.5

100.0

60.425.713.9

100.0

77.67.914.5

100.0

ANALYSIS OF PIGMENT.Per cent. Per cent.

White leadLead sulphate 39.26 18.13Zinc oxide 34.20 34.04Calcium carbonate .... 5.39 41.09

Barytes 19.90 6.20Undetermined color, etc. . 1 . 25 . 54

Per cent. Per cent.

17.7733.5839.886.402.37 1

14.2337.5741.706.100.40

100.00 100.00 100.00 100.00

346. ANALYSES BY AUTHOR OF MIXED PAINTS FORINSIDE USE.

I.

InsideWhite.

II. III.

InsideWhite.White.

Net weight, Ibs. and oz 3:0 15 : 14 : 2

Capacity of can, qts 1.04 0.30 0.30

Contents, qts 0.99 0.26 0.24


Pigment 62.9 28.3 62.8Vehicle 37.1 71.7 37.2

100.0 100.0 100.0

VEHICLE.Per cent. Per cent. Per cent.

Linseed oil 60. 1 2 68. 6 2 77.9

Turpentine 39.9 30.0 22.1Water 0.0 1.4 0.0

100.0 100.0 100.0

PIGMENT.*"

. Per cent. Per cent. Per cent.

White lead 18.84Lead sulphate 2 . 57Zinc oxide 70 . 27 99 . 80 80 . 45Lithopone 26 . 33Barium sulphate 20 . 12Zinc sulphide 6. 13

Silica . 28Undetermined . 0.55 0.20 00.71

100.00 100.001 Color largely organic.2 Includes a small amount of dammar varnish.

100.00


347. ANALYSES OF CHEAPENED MIXED PAINTSBY.THE AUTHOR.

Showing the various devices used for cheapeningthe cost of production, short volume, low pigment

content, practical absence of all lead pigments, excessive

use of drier, high per cent of water and of cheap inert

pigments. Two of these brands were sold as straight

white lead and zinc oxide paints.

III.

LeadColor.

9:93.372.42

Per cent.

67.1032.90

100.0

Per cent.

83. 9 1

4.311.8

100.0

100.00

4.7324.344.47

66 .'26

6.20

100.00 100.00

IV.

SlateColor.

5:121.901.85

Per cent.

50.849.2

100.0

Per cent.

61.922.016.1

100.0

Per cent. Per cent.

0.7460.1021.11

16.251.80

100.00

Very low-grade linseed oil.

CHAPTER XVIII.

KALSOMINE, COLD-WATER PAINTS, AND FLAT WALLFINISHES.

348. Kalsomine. Kalsomines may be divided into

two classes, those which require hot water to de-

velop their adhesive strength and those which maybe mixed with cold water, the glue having been so

treated as to be soluble in cold water. Kalsomines of

the latter class are more convenient to use but moredifficult to manufacture. Either class, however, con-

sists essentially of glue and one or more of the following

inerts, whiting, china clay, gypsum, magnesium silicate,

together with the necessary tinting colors.

349. The essential qualities of a good kalsomine

are:

1. Ease of preparation with water, with quick de-

velopment of adhesive strength.

2. Opacity and freedom from chalking.

3. Absence of brush marks and lap streaks on appli-

cation.

4. Maintenance of"sweetness

"for at least 3 days

after having been mixed with water.

.- 5. Permanence of tints.

350. Whiting is undoubtedly the best white base for

kalsomine, as it possesses the greatest body, the other

three inerts being more transparent, but spread easier

under the brush, so that the majority of kalsomines

contain besides the whiting a percentage varying from20 to 40 of these other inerts. Chalking is caused byusing an insufficient amount of glue or having weakened

163


the strength of the glue by the excessive use of pre-

servatives, a certain amount of which must be used in

order to maintain the"sweetness

"for several days

after a batch has been mixed with water, as the price

at which kalsomine is sold precludes the use of high-

priced glues. The best and most generally used pre-

servatives are aluminum sulphate and zinc sulphate,

and, as above stated, their excessive use weakens the

glue. When mixed with water, a kalsomine should

"jell" properly, and when applied on a wall the edgesof the first section should not dry before the next sec-

tion is started, else the lap will show. The retarding

of the drying of a kalsomine can be accomplished bythe use of Irish moss.

351. Permanence of tints is secured by avoiding colors

which are affected by the alkali action of the lime in

the plaster, especially Prussian or Chinese blue and

chrome green, using in their place, as much as possible,

blue and green lakes, which are known as "lime proof."

The various yellows are obtained by the acid of ocher

and the chrome yellows; the reds with the iron oxide

pigments, para reds precipitated on an inert base and

to some extent other organic reds;the greens with lime-

proof green lakes and chrome greens, although the lat-

ter are not permanent; the blues are lime-proof blue

lakes and ultramarine blue. The intermediate colors

are obtained by intermixing the above and with the

aid of the siennas, umbers, and blacks.

352. Analysis. The analysis of kalsomines offers no

particular difficulties, the percentage of glue being ob-

tained by running a nitrogen determination by the

Kjeldahl method and multiplying by the factor 0.37.

Zinc sulphate and aluminum sulphate are detected and

estimated in the usual manner; the white base and

KALSOMINE, COLD-WATER PAINTS, ETC. 165

tinting colors by the usual analytical methods, the

percentage of lake colors being obtained by difference.

353. The following analyses made by the author are

representative of several of the leading combinations on

the market :

i. ii.

White. White.

Per cent. Per cent.

Whiting 63.7 68.2China clay 16.3 9.1

Gypsum 10.1 15.5Glue 5.5 4.0Aluminum sulphate 1.4 2.1Moisture 2.5 0.4Ultramarine blue trace

Undetermined 0.5 0.7

100.0 100.0

Yellow Tint.

Per cent.

Whiting . 60.1China clay 15.0

Gypsum 11.3Ocher 2.4Lead chromate 2.4Moisture 1.9Glue 5.1Alum sulphate 0.9

100.0

Solid Wall Red.

Per cent.

Clay 22.2Red lake 9.4Barium sulphate 63 . 1

Glue 4.9Moisture 0.4

100.0

354. Lakes. The lime-proof lakes used are usually on

a barium carbonate or sulphate base, less commonly on

a silica or silicate base, and this base in the case of solid

wall colors, so-called, will constitute the larger portionof the kalsomine.


355. Testing. Hot-water kalsomines are prepared bysimply grinding together the glue, white base, and tint-

ing colors, after mixing in a high-speed rotary mill. In

the manufacture of the cold-water kalsomines the glue

is given a special treatment to render it soluble in cold

water before it is incorporated with the pigments, the

mixing and grinding being accomplished in the usual

manner. The testing of the glue for strength and

sweetness is a most important consideration, especially

in the manufacture of cold-water kalsomines. Themethod adopted by the author is to prepare a small

batch of kalsomine according to the regular formula,

incorporating the ingredients in the mixer and grind-

ing in the mill in the usual manner, the glue, how-

ever, being the one item omitted completely, and the

base so obtained is kept in the laboratory for testing

purposes. The weighed sample of the glue which

has been melted in the calculated amount of hot water

is cooled to room temperature and the requisite amountof kalsomine base added, care being taken to obtain a

mix free from lumps. A portion is brushed out uni-

formly on a sheet of unglazed paper, allowed to dry,

and the adhesiveness noted by rubbing and by the

folding of the paper. The remainder is allowed to

stand loosely covered in the laboratory for 3 days, it

then being stirred up and the"sweetness" noted. It

is a peculiar fact that a glue which when melted up in

water and allowed to jell will keep sweet by itself for

3 days may undergo marked decomposition in 36 hours

when incorporated with the pigment portion of the

kalsomine. Usually the deep tints and solid wall colors

will not require the addition of a glue preservative, as

the tinting colors themselves will prevent the decom-

position of the glue.

KALSOM1NE, COLD-WATER PAINTS, ETC. 167

356. Cold-water paints. The paints which come under

this head are prepared very much like kalsomine except

that the binding agent instead of glue is casein, together

with sodium carbonate or quicklime or both, which are

added in the dry form, the combination with the casein

being affected on the addition of water when being pre-

pared for use. The tints are usually restricted to those

obtained with ochre, blacks, and cheap Venetian reds.

Unless kept in a tight package cold-water paints will

lose their strength, as the quicklime will absorb carbon

dioxide from the air, becoming inert. Caustic soda is

sometimes used, but possesses marked disadvantages.

357. Analyses. The following analyses by the author

afford some idea of the composition of this class of

paints:i. n.

Outside White. Inside White.

Per cent. Per cent.

Whiting 55.55 60.60

Clay 13.90 14.12Calcium sulphate 13.65 16.08Casein 9.03 6.05Calcium oxide 4.72 1.51Sodium hydroxideSodium carbonate 3.15 1.64Ultramarine blue . trace

100.00 100.00

358. Specifications for Cold-Water Paint, Navy Depart-

ment, 1908.

1. Cold-water paint shall consist of whiting, 20 to

25 per cent silicious matter, free lime equivalent to

from 5 to 10 per cent of calcium hydrate, Ca(OH)2 ,and

from 10 to 12 per cent of casein, with not more than

traces of calcium sulphate and small amounts of zinc

oxide.

2. It must be capable of readily remixing at the endof fifteen hours after having been mixed in proper pro-


portions with cold water, and must not possess anoffensive odor.

3. When dry the paint must be of white color, andnot chip, scale, powder, or rub off when washed with

cold water, and in these regards must be equal to

standard sample.

359. Flat wall finishes. During the last few yearsthere has been developed a demand for a flat wall finish

similar to that produced by kalsomine, but capableof being washed and cleaned and not affected bymoisture.

360. The pigments used for this purpose must have

a high degree of opacity, lithopone perhaps beingthe one most used for the white and as a base for

the tints, although Paris white and gypsum mayreplace the lithopone in some of the tints, espe-

cially the yellows and greens. The most permanentblues are obtained with ultramarine; lime-proof reds

are used where possible; and the yellow tints are pro-

duced with chrome yellow and to some extent with

ocher.

361. The ratio of vehicle to pigment is much the

same as in ordinary mixed paints. The desired flat

effect is obtained by the use of a large percentageof volatile thinners, which will constitute about 75

per cent of the vehicle. The volatile thinners used

may be a mixture of turpentine and benzine, or tur-

pentine and petroleum spirits, or petroleum spirits

only.

362. The remaining portion of the vehicle, which is

just sufficient in quantity to act as a binder for the

pigment, may be a special varnish or a mixture of

boiled oil and a varnish, such as a linseed oil-rosin

varnish.

KALSOMINE, COLD-WATER PAINTS, ETC. 169

363. Analyses. The following analyses are typical of

this class of finishes :

White. Yellow.

Per cent. Per cent.

Lithopone 68.4 12.1

Gypsum 24.0Chrome yellow 23 . 9Petroleum thinner 23 . 5 29 . 7Linseed oil and varnish 8.1 10.3

100.0 100.0

CHAPTER XIX.

COMPOSITION OF COLORED PAINTS.

364. Lack of uniformity. After the extraction of the

vehicle it is necessary to examine the pigment quali-

tatively in order to ascertain the ingredients to be

determined. The usual qualitative scheme may be

followed with advantage. The colors, as given on the

color cards of paint manufacturers, are usually confined

to a limited number of combinations, the possible com-

ponents of which may be easily ascertained, and which,in fact, are usually well known to paint chemists; but

to the chemist who has had but little experience along

paint lines, the following tables of color ingredients will

be of interest. Unfortunately, manufacturers are not

agreed among themselves as to standards for namingcolors; for example, a tea green put up by one manu-facturer may not correspond with a tea green put up

by another; but, by a careful study of the color cards

issued by reputable paint manufacturers, it is usually

possible to identify the color to be analyzed. Also the

same or nearly the same color may be produced bydifferent combinations of color pigments, hence it is

necessary to state all of the possible constituents that

may be used, as far as the author has been able to

ascertain them, even though it is quite probable that

they may not all be present in the same paint.

365. Reds:

Brick. Base white, ochre and Venetian red.

Flesh Color. Base white, ochre, Venetian red, and

sometimes orange chrome yellow.170

COMPOSITION OF COLORED PAINTS. 171

Indian Red. Indian red.

Lilac. Ultramarine, carmine, Indian red, ochre, lamp-black.

Maroon. Carmine, ultramarine, lampblack, Tuscan

red.

Pink; Base white, orange chrome yellow.

Terra Cotta. Base white, burnt sienna, umber,chrome yellow, Venetian red, ochre.

Salmon. Base white, vermilion, lemon chrome yel-

low, sienna, ochre, Venetian red, orange mineral.

Tuscan Red. Tuscan red, Indian red, Para vermilions.

Venetian Pink. Base white, Venetian red.

Venetian Red. Venetian red.

366. Blues:

Azure Blue. Base white, ultramarine blue, chrome

green, Prussian blue.

Bronze Blue. Black, Prussian blue.

Dark Blue. Base white, chrome green, Prussian

blue, ultramarine, black.

Light Blue. Base white, ultramarine, Prussian blue.

Neutral Blue. Base white, Prussian blue, umber,black.

Robin's Egg Blue. Base white, ultramarine, lemon

chrome green.

Sky Blue. Base white, cobalt blue, Prussian blue,

ultramarine blue, chrome yellow.

367. Yellows:

Buff. Base white, ochre, black, red chrome lead.

Canary. Base white, lemon chrome yellow, chrome

green.

Citron. Base white, Venetian red, Prussian blue,

chrome yellow.


Cream. Base white, ochre, Venetian red.

Deep Cream. White, ochre, Venetian red.

Ecru. Base white, ochre, chrome yellow, black,

chrome green.

Ivory. Base white, chrome yellow, ochre.

Lemon. Base white, chrome yellow.

Manilla. Base white, ochre, chrome yellow.

Stone. Base white, ochre, umber, chrome yellow.

Straw. Base white, chrome yellow, ochre, Venetian

red.

368. Greens:

Ivy Green. Ochre, lampblack, Prussian blue.

Light Green. White, Prussian blue, chrome green.

Manse Green. Chrome green, chrome yellow, ochre.

Moss Green. Base white, ochre, chrome green, lamp-black.

Olive Green. Lemon chrome yellow, ochre, ultrama-

rine blue, Prussian blue, Indian red, chrome green,

lampblack.Pea Green. Base white, chrome green, very rarely

emerald green.

Sap Green. Base white, chrome yellow, lampblack,chrome green.

Sea Green. Base white, chrome green, sienna, ochre.

Tea Green. Base white, chrome green, chrome yel-

low, lampblack.Willow Green. Base white, chrome green, umber,

ivory, black.

369. Browns:

Acorn Brown. Sienna, carmine, Indian red, lamp-

black, ochre.

Brown. Indian red, lampblack, ochre.

COMPOSITION OF COLORED PAINTS. 173

Chocolate. Similar to acorn brown.

Cork Color. Base white, ochre, Indian red, lamp-

black, umber.

Dark Drab. Base white, Indian red, lampblack,Prussian blue, yellow ochre.

Doe Color. Base white, sienna, umber, ochre, lamp-black.

Dove Color. Base white, Prussian blue, lampblack,

ochre, Indian red, umber, sienna.

Drab. Base white, umber, Venetian red, yellow ochre,

black.

Fawn. Base white, ochre, Indian red, lampblack,

sienna, umber, chrome yellow, Venetian red.

Lava. Base white, black, chrome orange, chrome

yellow.

Sandstone. Umber.

Snuff Brown. Base white, ochre, Indian red, Vene-

tian red.

370. Greys and grays:1

Ash Gray. Base white, ochre, lampblack, sienna,

ultramarine blue.

Dark Slate. Base white, Prussian blue, lampblack.French Gray. Base white, black, ultramarine Prus-

sian blue, Venetian red.

Granite. Base white, ochre, lampblack.

Graystone. Base white, black, Prussian blue, ultra-

marine, Venetian red.

Lead. Base white, lampblack, Prussian blue.

Light Grey. Base white, lampblack, Prussian blue.

1Grey is understood to mean an admixture of black and white,

while gray is an admixture of black and white to which another color

has been added, provided, of course, that the black and white pre-

dominate.


Pearl. Similar to French gray.

Silver Gray. Base white, ochre, lampblack, chrome

yellow.

Smoke Gray. Base white, ochre, lampblack.

Steel Gray. Base white, chrome yellow, lampblack.

Stone Gray. Base white, chrome yellow, black.

Warm Gray. Base white, ochre, lampblack, sienna,

Prussian blue.

CHAPTER XX.

ANALYSIS OF INDIAN REDS, VENETIAN REDS, TUSCANREDS, RED OXIDES, AND OCHRES.

371. Hygroscopic moisture. Heat 2 grams at 105 C.

for 3 hours. Loss in weight represents hygroscopic

moisture.

372. Combined water, etc. Transfer above sampleto a weighed platinum crucible and heat for one hour

over an ordinary lamp, or better in a muffle. Loss in

weight indicates amount of combined water. Carbon-

ates and organic matter render the results inaccurate,

in which case continue the ignition at bright red heat

for several hours, and weigh again. Determine the

carbon dioxide in another portion of the sample and

estimate the combined water by difference. If a large

amount of calcium sulphate is present, it is possible to

heat it strongly enough to partially drive off the com-

bined sulphuric acid, and unless this be taken account

of the analysis will total up to more than 100 per cent.

In the case of a Tuscan red which has precipitated uponit an organic color, the loss in weight is best reported

as combined water and organic matter. The presence

of .an organic color may always be detected by the

characteristic odor given off at the beginning of the

ignition.

373. Silica and barium sulphate. One gram of the

pigment is intimately mixed with 6 to 8 grams of potas-

sium bisulphate and fused in a large porcelain crucible,

the cover of which is small enough to set inside the top

of the crucible, at not too high a temperature for one-

175


half hour, finally heating the side of the crucible to

finish the conversion of any material adhering to the

cover and upper portion of the crucible. The iron,

aluminum, calcium, and magnesium are converted into

sulphates, the barytes remains unchanged and the silica

is completely dehydrated. With a little care, using a

low heat at first, the fusion may be conducted with verylittle frothing or spattering. Fusion with bisulphate is

to be preferred to solution with hydrochloric acid, as

ferric chloride is appreciably volatile on boiling. Also

the silicates of iron that are present in small quantityin the natural oxides are not decomposable with hydro-chloric acid.

After cooling, the entire contents of the crucible maybe shaken loose and dissolved in sufficient water and a

little hydrochloric acid. Filter and make up to 250 c.c.

unless calcium is present in large amount, in which case

make up to a volume of not less than 500 c.c., as calcium

sulphate is but sparingly soluble.

The residue remaining on the filter is ignited and

weighed in a platinum crucible. The residue is tested

for barium sulphate by the flame test: if absent the

residue is reported as silica; if present the residue is

treated in the crucible with hydrofluoric acid until a

thin paste is formed. The mixture is stirred with a

platinum wire and digested at a gentle heat; finally two

or three drops of sulphuric acid are added, and the

temperature gradually raised until no further loss in

weight takes place, indicating that the silica has been

completely expelled. The residue is weighed as barium

sulphate, and the loss in weight represents the silica,

or the residue of barium sulphate and silica may be

fused with sodium carbonate as described under the

analysis of white pigments.

ANALYSIS OF INDIAN REDS, ETC. 177

374. Ferric oxide. An aliquot portion of the solution

from 373 is heated to boiling and stannous chloride

solution added cautiously until the yellow color has

disappeared, and then a slight excess added. All at

once, with vigorous shaking of the flask, 50 c.c. of mer-

curic chloride solution is added, then 50 c.c. of the

manganous sulphate solution. Dilute with cold fresh-

boiled water and titrate with permanganate solution.

Calculate iron found to ferric oxide.

375. Preparation of reagents.

a. Stannous chloride. Dissolve 30 grams of tin in

250 c.c. of hydrochloric acid, filter through glass wool,

and make up to one litre.

b. Mercuric chloride. Dissolve 50 grams in one litre.

c. Manganous sulphate. One litre should contain 66.7

grams of crystallized manganous sulphate, 333 c.c.

phosphoric acid (sp. gr. 1.3), and 133 c.c. of cone, sul-

phuric acid.

d. Potassium permanganate. Dissolve 3.16 grams in

one litre; standardize against the standard iron solution.

e. Standard iron solution. Dissolve 7.03 grams iron

wire, 99.7 per cent purity, in dilute hydrochloric acid;

make to one litre.

1 c.c. = 0.01 g. ferric oxide or 0.007 gr. iron.

In many cases where a rapid commercial determina-

tion of the iron content alone is desired, the pigment

may be dissolved in hydrochloric acid, with the subse-

quent addition of a few drops of nitric acid, filtered,

the iron and alumina precipitated with ammonia; after

thorough washing dissolved in sulphuric acid, run

through a "redactor," such as may be obtained from

any of the leading supply houses, and then simplytitrated with standard permanganate solution in the

usual manner.


376. Alumina. An aliquot part of the solution in 373

is made just alkaline with ammonia, boiled, decanted,

filtered, washed, redissolved, reprecipitated, filtered,

ignited, and weighed as alumina and ferric oxide, the

alumina being obtained by difference.

377. Calcium. The filtrate from the iron and alumina

is treated with ammonium oxalate (50 c.c. is sufficient

for 1 gram of calcium pigment). Set aside in a warm

place for two or three hours, filter, ignite, and weigh as

calcium oxide, or titrate with standard permanganate,as may be desired. The calcium may have been present

as carbonate or sulphate or both. Hence an estima-

tion of the sulphur trioxide present in the original sampleis necessary. For this purpose 1 gram is dissolved in

30 c.c. of strong hydrochloric acid, boiled 10 minutes,

diluted with 50 c.c. of water, heated to boiling, filtered,

and washed with hot water. Neutralize the filtrate

with ammonia, then make just distinctly acid with

hydrochloric acid, boil, add 10 c.c. of barium chloride

solution, continue boiling for 10 minutes, filter, wash,

ignite, and weigh as barium sulphate. Calculate sul-

phur trioxide by multiplying weight of precipitate by0.343.

Calculate the sulphur trioxide found to calcium sul-

phate and the remaining calcium to oxide, provided

that the carbon dioxide is included under loss on igni-

tion. If desired, the remaining calcium may be cal-

culated to calcium carbonate, the combined carbon

dioxide being deducted from the loss on ignition.

378. Magnesium. If a considerable percentage of cal-

cium is found, magnesium is liable to be present ; precipi-

tate with sodium hydrogen phosphate in usual manner.

Calculate the pyrophosphate to oxide by multiplying

by the factor 0.3624.


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380. Tuscan reds should contain about 60 per cent

ferric oxide, and are often brightened up by having

precipitated on them an organic red. Another class of

oxides, carrying about the same amount of iron oxide

as Tuscan reds, is"Prince's metallic/' The variation

of iron content is shown in the following analyses:

No. Ferric Oxide.

I. 44.07II 38.17 .

Ill 68.45IV 49.58V 39.35

A complete analysis gave the following:

Per cent.

Volatile 3.33Ferric oxide 40 . 91

Alumina 3.49Calcium oxide 2.00Insoluble 49.57Undetermined . 0.70

100.00

381. Ochres, of which the French ochres are consid-

ered the best, to pass inspection by the various service

department scientists of the United States Government,must be of good bright color, contain at least 20 per cent

sesquioxide of iron and not over 5 per cent of lime in

any form. A good grade of yellow ochre to pass this

inspection would analyze about as follows:

Per cent.

Silica 52.14Alumina 12.89Ferric oxide 22.42Calcium oxide 0.36Combined water 10.16

Hygroscopic water 2 . 03

100.00


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Specifications for Venetian Red.

(Bureau of Supplies and Accounts, Navy Department, 1902.)

383. Red, Venetian. I. Red, Venetian (bright). The

dry pigment must contain at least 20 per cent of sesqui-

oxide of iron, not more than 15 per cent of silica, the

balance to consist of sulphate of lime that has been fully

dehydrated by dead burning, and rendered incapable of

taking up water of crystallization.

II. Red, Venetian (deep). The dry pigment must

contain at least 30 per cent of sesquioxide of iron, not

more than 15 per cent of silica, the balance to consist of

sulphate of lime that has been fully dehydrated by dead

burning and rendered incapable of taking up water of

crystallization.

III. Red, Venetian (medium). The dry pigmentmust contain at least 40 per cent of sesquioxide of iron,

not more than 15 per cent of silica, the balance to con-

sist of sulphate of lime that has been fully dehydrated

by dead burning and rendered incapable of taking upwater of crystallization.

384. Priming ochres. A few years ago the adultera-

tion of priming ochres, so called, was exceedingly wide-

spread. Paint legislation has done much to check this

evil, and in such states as require the label to show the

ingredients and percentages thereof, the sale of this

class of goods has largely diminished, and the author

believes very few property owners would care to use

the cheap combination priming ochres with which the

market is flooded. It is just as useless to expect the

coats of paint applied over such primers to give a

satisfactory service value as it is to expect a house to

stand, built on a foundation of rubbish.


385. Analysis. The analysis of this class of goods

may be performed substantially as described in this

chapter. The vehicle should receive careful examina-

tion, as these so-called ochres are often ground in par-

affin oil, low-grade linseed oil containing large quanti-

ties of foots, or in soya-bean oil. The names under

which such goods are placed on the market are also

misleading, as white ochre, stone ochre, etc. The nature

of some of these products is indicated by the following

analyses :

i.

Per cent.

Barium sulphate 36.24Calcium carbonate 47 . 79Aluminum silicate and silica 3 . 87Iron oxideLinseed oil 12.10

Naphtha

100.00 100.00i Ochre.

386. Tinting ochres. Under this head are included

pure French ochres ground in linseed oil, ochres which

have precipitated on them a small percentage of chrome

yellow, and various mixtures of ochre, chrome yellowand inert pigments like barytes, white mineral primer,

etc. When toned up with chrome yellow, these various

combinations are sold under some such name as golden

ochre, topaz ochre, etc. The following analyses calcu-

lated to formula indicate the nature of some of these

combinations :

i. n.Per cent. Per cent.

Ochre 63.58 40.60Chrome yellow 2.13 8.91

Barytes 7.69

Gypsum 34.29 ...

Calcium carbonate 42 . 80

100.00 100.00


387. Domestic ochres. It has been stated that the use

of cheap domestic ochres, of low tinting strength, fur-

nished a ready means of cheapening mixed paints in

which yellow tinting colors were required, by the intro-

duction of a large amount of inert material along with

the color. This condition of affairs the author believes

to be very improbable, as the color value of the domes-

tic ochres is very unlike the accepted grades of French

ochres, in that they do not produce clean, clear tints

or give pleasing effects, and therefore the bother and

trouble in handling domestic ochres is of greater momentthan the difference in price.

CHAPTER XXI.

ANALYSIS OF BLACK PIGMENTS AND PAINTS.

388. Composition. The ordinary black pigments

lampblack, vegetable black, bone black, ivory drop

black, gas black, graphite, etc. contain carbon as their

essential constituent, and while all of these products

are said to be of a black color, they vary greatly in

shade and still more so in tinting strength.

1. Lampblack and vegetable black are essentially

soot blacks, being the soot deposited from the combus-

tion of oily bodies such as dead oil. Lampblack has a

distinct gray tint, as may be shown by comparison with

ivory black. These blacks are apt to contain varying

quantities of oil, owing to the nature of their manu-

facture; less than 1 per cent of oil often being suffi-

cient to retard seriously the drying of lampblack paints.

Vegetable blacks are more voluminous than lampblacksand are usually of a jet black color.

2. Carbon black is usually produced from the in-

complete combustion of natural gas. While its tinting

power is very great, its use has been largely abandoned

owing to its tendency to produce a streaky color whenused in tinting paints.

3. Bone black is, as its name indicates, obtained bythe charring of bones in retorts. The carbon content

varies usually between 12 and 22 per cent, the balance

consisting of moisture, phosphate of calcium, and car-

bonate of calcium. The best grades of bone black

are made from selected sheep bones. An exceedingly185


intense black is made by digesting selected bones in

hydrochloric acid until all of the mineral matter is dis-

solved, leaving the carbon in a flocculent state. This

black is often sold under the name of black toner, and

is one of the highest priced blacks.

4. Animal black is a name sometimes given to bone

black but is also used to designate a wide variety of

blacks prepared in the same way as bone black from

waste animal products of all kinds, as leather scrap

parings, horn trimmings, etc.

5. Frankfort black, drop black, and German black

are terms used to designate blacks made from a variety

of organic materials, such as vine twigs, refuse of wine

making, peach stones, bone shavings, etc. These

blacks vary in hue from a bluish black to a reddish

black.

6. Graphite, while not used to any extent in house

paints, is largely used in bridge, elevator, and warehouse

paints. It is rarely used by itself for these purposes,

silica, calcium carbonate and iron oxide pigments, zinc'

and lead being the other usual constituents. It maybe tested qualitatively in the extracted pigment by

rubbing a portion of the sample between the palms,

which soon assume the characteristic appearance pro-

duced by stove polish. Of all the black pigments

graphite alone gives this test.

7. Charcoal black and vine black are produced bythe charring of wood products, and contain besides

carbon the ash ingredients common to wood. Char-

coal blacks are usually made from maple, willow, and

basswood, and vine blacks from the charring of the

grapevine. Paints containing considerable quantities

of these blacks are liable to saponify badly owing to the

moisture and potash salts present.

ANALYSIS OF BLACK PIGMENTS AND PAINTS. 187

8. Mineral black, which is still occasionally used, is

black slate finely ground.

389. Moisture. Dry 2 grams at 105 C. for 3 hours.

Loss in weight represents approximately the amount of

moisture present.

390. Oils. Extract 2 grams with ether in a fat extrac-

tion apparatus. After removing the ether and drying,

any increase in weight represents the amount of oily

matter present.

391. Ash. Two grams are weighed into a crucible

and heated over a Bunsen burner until all the carbon

is burned off. If the ash constitutes only a small per

cent, it may be cooled and weighed directly. Other-

wise the residue is moistened with a solution of ammo-nium carbonate, heated gently, and weighed. The

object of this operation is to restore the carbon dioxide

which may have been expelled from the bases by the

strong heat to which they have been subjected.

392. Carbon. The carbon is usually estimated by dif-

ference, by adding together the moisture, oil, and ash,

and subtracting from 100.

393. Calcium. Digest the residue from 391 in a mix-

ture of 25 c.c. of concentrated hydrochloric acid and

5 c.c. of concentrated nitric acid on the hot plate for

one-half hour, dilute, filter, and make up to 250 c.c. in

a graduated flask. Any appreciable residue on the

filter may indicate addition of barytes, silica, clay, or

alumina. Determine the calcium and magnesium in an

aliquot portion of the solution by adding ammonia in

small quantities until a precipitate is formed, then

acetic acid in excess until redissolved, except for traces

of iron which may be removed by filtration. Ammo-nium oxalate is added, and the calcium precipitate

treated in the usual manner.


394. Phosphoric acid. Take an aliquot portion of the

solution prepared above, neutralize with ammonia, and

clear with a few drops of nitric acid, add about 5 gramsof dry ammonium nitrate or a solution containing that

amount. To the hot solution add 50 c.c. of molybdicsolution for every decigram of phosphoric acid that is

present. Digest at about 65 for an hour, filter, and

wash with cold water, or preferably ammonium nitrate

solution. Test the filtrate for phosphoric acid byrenewed digestion and addition of more molybdic solu-

tion. Dissolve the precipitate on the filter with am-

monia and hot water, and wash into a beaker to a bulk

of not more than 100 c.c. Nearly neutralize with

hydrochloric acid, and add magnesia mixture from a

burette; add slowly (about 1 drop per second), stirring

vigorously. After 15 minutes add 30 c.c. of ammoniasolution of density 0.96. Let stand for some time;2 hours is usually enough. Filter, wash with 2.5 per

cent ammonia, ignite to whiteness or to a grayish

white, and weigh as magnesium pyrophosphate.

395. Preparation of reagents. Molybdic solution. Dis-

solve 100 grams of molybdic acid in 400 grams or

417 c.c. of ammonia, specific gravity 0.96, and pour the

solution thus obtained into 1500 grams or 1250 c.c. of

nitric acid, specific gravity 1.20. Keep the mixture in

a warm place for several days, or until a portion heated

to 40 deposits no yellow precipitate. Decant the

solution from any sediment and preserve it in glass-

stoppered vessels.

Magnesia Mixture. Dissolve 110 grams of crystal-

lized magnesium chloride, 280 grams of ammonium

chloride, in 700 c.c. of ammonia of specific gravity 0.96,

and sufficient water to make 2000 c.c.

396. Magnesium. The filtrate, from which the cal-


cium has been precipitated, is evaporated to a small

bulk and made alkaline with ammonia. After stand-

ing several hours tlie magnesium precipitate is filtered,

ignited, and weighed, and calculated to magnesium by

multiplying by 21.88.

397. Calculations. The magnesium is calculated to

magnesium phosphate, and the remainder of the phos-

phoric acid to calcium phosphate. Any calcium re-

maining is calculated to calcium carbonate.

Genuine ivory black, made by carbonizing waste frag-

ments and turnings of ivory, is often adulterated with

bone black, which is somewhat similar in composition,

but contains only a small amount of magnesium phos-

phate as compared with the ivory black.

398. Specifications for drop black. (Navy Depart-

ment, May, 1903.) Drop black must be of good deepluster and consist of calcined bone black only. Theaddition of blue or gas carbon black will be ground for

rejection. The paste must contain not less than 45

per cent of pure pigment.The pigment must be of the best quality, free from

all adulterants, and equal in all respects to the standard

sample.

The paste must be ground in pure raw linseed oil

only, to a medium stiff paste, which will break upreadily in thinning.

399. Specifications for carbon black, etc. (Treasury

Department, 1907.) Carbon black must be pure gascarbon with not more than 0.5 per cent of ash, that is,

97.5 per cent of pure carbon and the balance moisture,

ash, etc.

Hard black; should be suitable for making the high-est class of plate printing inks; and other factors being

equal, a color having chemical and physical properties


adapted for that purpose and which produces an ink

having the most satisfactory working qualities will be

selected. The black now in use has the following

chemical analysis:Per cent.

Ash 48.3Moisture 3.7Carbon 48.0

Ash insoluble in hydrochloric acid 11.4 per cent.

Soft Black. Requirements same as for hard black.

The black in use has the following chemical analysis:

Per cent.

Ash 56.1Moisture 2.5Carbon (by diff.) 41.4

100.0

Ash insoluble in hydrochloric acid 36.3 per cent.

400. COMPOSITION OF IVORY AND BONE.

IVORY (Uncakined).

I. II.

Per cent. Per cent.

Calcium phosphate, including slightamount of calcium fluoride 38 . 48 46 . 48

Calcium carbonate 5 . 63 3 . 86

Magnesium phosphate 12.01 7.84Soluble salts 0.70 0.77

Organic matter 43.18 41.05

100.00 100.00

BONE (Uncakined').I. II.

Per cent. Per cent.

Calcium phosphate 61.4 62 . 4Calcium carbonate 8.6 7.9

Magnesium phosphate 1.7 1.7

Organic matter 28 . 3 28 .

100.0 100.0


401. TYPICAL ANALYSES BY THE AUTHOR OF THEVARIOUS BLACKS.

Oil

AshIi

CCMagnesium phos-

phate 0.38Carbon .

0.3810.10 12.63

0.96

100.00 100.00

1 Not true ivory blacks.

12.57

100.00

Analysis of Mixed Paints Tinted with Black and Oxide

of Iron Pigments.

402. Carbon. One gram of the pigment is dissolved

in hydrochloric acid as described under white pigments,

and the residue filtered through an ashless filter, that has

been dried in the hot-water oven and weighed. After

washing the residue with boiling water the filter and

contents are dried and weighed, then ignited until all

the carbon is burned off, and weighed again. The per-

centage of carbon is obtained by difference. Wherethe percentage of color is small, it is often estimated bydifference, adding together the determined constituents

and subtracting from 100.

403. Ferric oxide. If the filtrate from the insoluble


residue is of an appreciable yellow color, it indicates

that the tint has been" warmed up" by the addition of

an ochre or oxide, in which case the lead is precipi-

tated and estimated as described under analysis of

white pigments, the nitrate from the lead sulphide

heated until all of the hydrogen sulphide has been

expelled and the iron and alumina precipitated with

ammonia after having been oxidized by boiling with a

few drops of nitric acid, filtered and ignited and weighedin a porcelain crucible, the residue fused with bisul-

phate of potassium, dissolved in water with the aid

of a little hydrochloric acid, heated to boiling, reduced

with stannous chloride; mercuric chloride and man-

ganous sulphate solution added and titrated with per-

manganate in the manner described under analysis of

Venetian reds.

404. Alumina. The alumina is calculated by differ-

ence from the data obtained under 403.

405. Zinc oxide. The filtrate from the iron and alu-

mina precipitate and the nitrate from the lead sulphate

precipitate, the alcohol having been removed by evap-

oration, are mixed, made distinctly alkaline with ammo-

nia, and the zinc precipitated with hydrogen sulphide.

The liquid containing the zinc sulphide precipitate is

heated to boiling, and about 5 grams of solid ammo-nium chloride added, which renders the precipitate

easier to filter. Settle, filter, and wash thoroughly.

Pierce filter, wash through into a clean beaker with

water, dissolving the residue on filter with dilute hydro-chloric acid, and wash with hot water. Dilute, heat to

expel hydrogen sulphide, and titrate with 'ferrocyanide

as previously described. If iron is absent in the paint

the zinc may be estimated directly as described under

analysis of white paints.


406. Calcium and magnesium. Estimate as usual in

the filtrate from the zinc sulphide.

407. Residue insoluble in hydrochloric acid. Fuse with

sodium carbonate as previously described. Dissolve in

water and filter. Iron not previously dissolved will

remain on the filter as ferric oxide along with anybarium that may be present. This residue after thor-

ough washing is dissolved with the aid of a small

quantity of hydrochloric acid, the barium precipitated

as usual, and the iron estimated in the filtrate from the

barium sulphate. The silica and alumina are estimated

as usual.

408. Lead sulphate. Determine the combined sul-

phuric acid as described under analysis of white paints

and calculate to lead sulphate in the absence of calcium

sulphate. If calcium carbonate and calcium sulphate

are both present the nitric acid-alcohol separation

should be used.

409. ANALYSES, BY AUTHOR, OF PAINTS TINTED WITHBLACKS, OCHRE, AND IRON OXIDES.

I. II.

Light Drab. Drab.

Net weight 61bs. 6oz. Gibs. 12 oz.

Capacity of can, qts 2.06 2.03Contents, qts 1.93 1.92

Per cent. Per cent.-

Pigment by weight 56.6 56.9'

Vehicle 43.4 43.1

100.00 100.00

ANALYSIS OF VEHICLE.Per cent. Per cent.

Linseed oil . . . 92.9 92.0Turpentine drier 7.0 6.2Water 0.1 1.8

100.0 100.0


ANALYSIS OF PIGMENT.Per cent. Per cent.

White lead 26.57 27.73Lead sulphate . 78 2 . 39Zinc oxide 62.34 57.12Color 10.31 12.76

Clay and silica 5.56 7.74Iron oxide 3 . 02 3 . 89Carbon and undetermined . 1 . 73 1.13

100.00 100.00

410. Graphite paints. The term graphite as applied to

paints does not necessarily mean that such paints are

composed of graphite wholly or even in part. In fact

there is no accepted standard of purity for graphite

itself. One paint manufacturer may purchase a nat-

ural graphite for his line of graphite paints which con-

tains 20 per cent of graphitic carbon, the other 80 per

cent being silica and various silicates; others may pur-

chase graphites containing 80 per cent or more of graph-

itic carbon;and some purchase products which are very

nearly pure graphitic carbon, prepared electrically.

While it is a far from settled question, perhaps the

majority of paint manufacturers and those who buy

graphite paints under strict specifications are of the

opinion that a graphite paint affords better service

value when it contains, in part something besides

graphitic carbon.

411. Colored graphite paints. Having established his

graphite paint on the market, the manufacturer soon

has requests for colors other than black, and in order

to meet the requirements of his trade he finds it neces-

sary to add considerable amounts of tinting pigments,

with the natural result that in time many of his formulas

contain little or no graphite.

412. The following analyses will give some idea of

the pigment combinations to be found on the market:


I. II. ill. IV.

Natural Olive Indian Seal

Graphite. Graphite. Red BrownGraphite. Graphite.

Per cent. Per cent. Per cent. Per cent.

Graphitic carbon 32.14 21.89 ... 5.31Calcium carbonate .... 42.86 19.16 44.59 26.12

Magnesium silicate and sili-

cate 25.00 ... 12.17 33.72Ochre 58.95Ferric oxide . ... ... 43.24 34.85

100.00 100.00 100.00 100.00

The pigment portion of one sample analyzed by the

author was nothing but Keystone filler; another, carbon

black, which while as expensive as the ordinary grades

of graphite is nevertheless radically different. Graphite

paints which are sold according to specifications for

structural iron and steel work are usually high-grade

products.

CHAPTER XXII.

ANALYSIS OF BROWN PIGMENTS AND PAINTS.

Vandyke-brown. Composition.

413. Vandyke-browns vary widely in composition

according to the method of preparation. Some are

obtained from natural deposits of an organic nature,

such as peat, decayed vegetable matter, etc.;or by the

slight calcining of cork cuttings, bark, and twigs of trees;

while some of the more common varieties are prepared

by mixing lampblack or other black pigments with

sufficient red oxide and ochre to give the desired shade.

414. Analyses of two Vandyke-browns by the author

gave the following results :

i. IT.

Organic matter and moisture .... 90.95 91.10Ash 9.05 8.90

Silica 1.90 2.61Alumina and ferric oxide 1 . 43 1 . 50Calcium carbonate 4.98 3.28Soluble salts 0.74 1.51

100.00 100.00

Analysis of Umbers and Siennas.

415. Hygroscopic moisture. Heat 2 grams at 105 C.

for 3 hours. Loss in weight represents hygroscopic

moisture.

416. Combined water. Transfer above sample to a

weighed platinum crucible and heat for 1 hour over an

ordinary lamp, or better in a muffle. Loss in weight

indicates amount of combined water. Carbonates and

ANALYSIS OF BROWN PIGMENTS AND PAINTS. 197

organic matter render the results inaccurate, in which

case continue the ignition at bright red heat for several

hours, and weigh again. Determine the carbon dioxide

in another portion of the sample and estimate the com-

bined water by difference.

417. Silica and barium sulphate. One gram of the pig-

ment is intimately mixed with 6 to 8 grams of potassium

bisulphate and fused in a large porcelain crucible, the

cover of which is small enough to set inside the top of

the crucible, at not too high a temperature for one-

half hour; finally heating the side of the crucible to

finish the conversion of any material adhering to the

cover and upper portion of the crucible. The iron,

manganese, aluminum, calcium, and magnesium are

converted into sulphates, the barytes remains un-

changed, and the silica is completely dehydrated.

After cooling, the entire contents of the crucible maybe shaken loose and dissolved in sufficient water and a

little hydrochloric acid. Filter and make up to 250 c.c.

418. The residue remaining on the filter, which should

be white, a red or brownish color indicating incompletefusion with potassium bisulphate, in which case the

sample must be fused again, is ignited, and weighed in

a platinum crucible. The residue is tested for barium

sulphate by the flame test: if absent, the residue is

reported as silica; if present, the residue is treated in

the crucible with hydrofluoric acid until a thin paste is

formed. The mixture is stirred with a platinum wire

and digested at a gentle heat; finally two or three dropsof sulphuric acid are added and the temperature gradu-

ally raised until no further loss in weight takes place,

indicating that the silica has been completely expelled.

The residue is weighed as barium sulphate and the loss

in weight represents the silica.


419. Ferric oxide. An aliquot portion of the solution

from 417 is heated nearly to boiling and stannous chlo-

ride solution added cautiously until the yellow color has

disappeared, and then a slight excess added. All at

once with vigorous shaking of the flask 50 c.c. of mer-

curic chloride solution is added, then 50 c.c. of the

manganous sulphate solution. Dilute with cold fresh-

boiled water and titrate with permanganate solution.

Calculate iron found to ferric oxide.

420. Manganese. Digest 0.5 gram of the sample with

15 c.c. of concentrated hydrochloric acid until all of the

iron and manganese has dissolved, then add 5 c.c. of

sulphuric acid diluted with 10 c.c. of water, and evapo-

rate on the hot plate until all of the hydrochloric acid is

expelled as shown by copious evolution of sulphur tri-

oxide fumes. Cool, dissolve in about 25 c.c. of water,

and heat carefully with occasional shaking until all of

the anhydrous sulphate of iron has dissolved. Trans-

fer to a 250 c.c. graduated flask and add an excess of

zinc oxide emulsion, obtained by mixing C. P. zinc

oxide with water. Avoid a large excess, but sufficient to

precipitate all the iron, so that on standing the solution

begins to settle clear and some zinc oxide can be seen in

the bottom of the flask. Cool and make up to the mark.

421. Transfer an aliquot portion to a beaker or flask,

and add an excess of a saturated solution of bromine

water and about 3 grams of sodium acetate. One c.c.

of a saturated solution of bromine water will precip-

itate about 0.01 gram of manganese. Boil for about

2 minutes. Filter and wash with hot water. Thefiltrate must be perfectly clear. Place the filter con-

taining the washed precipitate back in the beaker or

flask in which the precipitation was made. All traces

of bromine must be entirely expelled.


422. Add an excess of standard oxalic acid solution

and about 50 c.c. of dilute sulphuric acid (1:9) and

heat nearly to boiling with gentle agitation until the

precipitate is entirely dissolved. Dilute to about 200

c.c. with hot water, and titrate with standard perman-

ganate.

Standard oxalic acid solution. Dissolve 12.6048 gramsof chemically pure oxalic acid in freshly boiled water and

make to 1000 c.c. in a graduated flask.

One c.c. of this solution = .0055 gram of manganese.

The oxalic acid solution should be standardized against

the standard permanganate solution and the correction

factor calculated.

Example: Wt. of sample taken = 0.5 gram.Volume of solution = 250 c.c.

Aliquot portion used = 100 c.c. = 0.2 gram.1 c.c. of permanganate sol. =

. 499 c.c. of oxalic acid.

1 c.c. of oxalic acid sol. = 0.0055 gram of manganese.

Permanganate solution used in titrating excess of

oxalic acid solution = 13.2 c.c.

13.2 c.c. =6.59 c.c. of oxalic acid.

Oxalic acid solution used, 10.00 c.c.

Excess, 6.59 c.c.

Consumed, 3.41 c.c.

3.41 x .0055 = .018755 g. Mn.Mn:Mn02 : . 018755 :z.

x =. 02967 g. Mn02 .

.02967 + 0.2 = 14.84 per cent Mn02 .

423. Alumina. Fifty c.c. of the 250 c.c. solution pre-

pared in 417 is treated with about 20 grams of solid


ammonium chloride, made just alkaline with ammonia,

heated, allowed to settle, decanted, filtered, and washed.

The precipitate is dissolved on the filter with hydro-chloric acid and, after washing with small portions

of boiling water, the iron and aluminum is repre-

cipitated, solid ammonium chloride being added as

before. The precipitate is washed by decantation, fil-

tered, and the filtrate collected in the beaker containing

the first filtrate. This treatment frees the iron and

aluminum from any manganese and the precipitate maybe dried, ignited, and weighed in the usual manner, the

alumina being obtained by difference. It is often ad-

visable to make another reprecipitation of the iron

and alumina, using but a small amount of ammoniumchloride.

424. Calcium and magnesium. The combined filtrates

from the iron and alumina are treated with colorless

ammonium sulphide in such a manner as to form the

green sulphide of manganese, which is very much easier

to filter than the pink sulphide.

The colorless ammonium sulphide may be preparedas follows: Saturate one-half of a solution of 100 c.c. of

water and 50 c.c. of ammonia (sp. gr. 0.90) with hydro-

gen sulphide, and then add the other half of the solu-

tion.

For the precipitation of the manganese, 25 c.c. of the

ammonium sulphide solution and 10 c.c. of ammoniumchloride solution containing 3 grams of the dry salt are

placed in an Erlenmeyer flask, the solution diluted to

about 100 c.c. and heated. As soon as it comes to a

boil, the combined filtrate from the iron and alumina

is added and the beaker rinsed with a little water.

The flask is shaken vigorously and the solution kept

nearly at the boiling point. After alternate shaking

ANALYSIS OF SHOWN PIGMENTS AND PAINTS. 201

and heating, the pink sulphide of manganese turns

green and settles readily, leaving a clear supernatent

liquid. If the ammonium sulphide is of the proper

strength and a sufficient amount be used, there should

be no difficulty in obtaining the green sulphide in

proper condition for filtering.

After filtering off the manganese, the filtrate is evap-orated to a syrupy consistency and 20 c.c. of nitric

acid (sp. gr. 1.2) added in small portions, evaporatingeach time. Sufficient hydrochloric acid is added and

heat applied, until the brown fumes cease to be givenoff. This treatment, which removes the excess of am-

monium salts, is not necessary if magnesium is knownto be absent.

The solution, after the removal of the nitric acid, is

diluted with water, made alkaline with ammonia, andthe calcium and magnesium separated and estimated

in the usual manner, both being calculated to the

oxides. The calcium may have been present as car-

bonate or sulphate or both. Hence an estimation of

the combined sulphuric acid present in the original sam-

ple is necessary. For this purpose 1 gram is dissolved

in 30 c.c. of strong hydrochloric acid boiled 10 min-

utes, diluted with 50 c.c. of water heated to boiling,

filtered, and washed with hot water. Neutralize the

filtrate with ammonia, then make just distinctly acid

with hydrochloric acid, boil, add 10 c.c. of barium

chloride solution, continue boiling for 10 minutes, filter,

wash, ignite, and weigh as barium sulphate. Calculate

combined sulphuric acid by multiplying weight of pre-

cipitate by 0.343.

Calculate the combined sulphuric acid found to cal-

cium sulphate and the remaining calcium to oxide.


425. ANALYSES OF UMBERS AND SIENNAS BY THE AUTHOR.I. ii.

Raw BurntSienna. Sienna.

Moisture 0.42 0.44Loss on ignition . 12.28 12.67Silica 36.85 19.55Ferric oxide 45 . 18 62 . 75Alumina 3.00 1.66Calcium oxide 1 . 09 2 . 52Magnesium oxide 0.85 0.00Sulphur trioxide 0.15 0.20Manganese dioxide 0.13 0.17Undetermined 0.05 0.04

100.00 100.00

III. IV.

Raw BurntUmber. Umber.

Moisture 1.78 2.01Loss on ignition 13.64 3.94Silica 20.60 24.21Ferric oxide 42.60 51.04Alumina 2.90 6.80Calcium oxide 3.68 1.95

Magnesium oxide 2.16

Sulphur trioxide 0.36 0.22Manganese dioxide 11.95 9.79Undetermined . 0.33 0.04

100.00 100.00

Analysis of Mixed Paints Containing Umbers,

Siennas, and Ochres.

426. Determine the manganese in a separate sampleas determined under the analysis of umbers. Deter-

mine the lead as in white paints, using the filtrate from

the lead sulphide for the estimating of the iron, which

must be oxidized by boiling with a little nitric acid be-

fore precipitating. Determine aluminum, zinc, calcium,

and magnesium as described under analysis of umbers

and siennas. The zinc being precipitated as the sul-

phide after the removal of the iron and aluminum is


contaminated with manganese sulphide. Dissolve the

mixed sulphides in dilute hydrochloric acid, boil until

the odor of hydrogen sulphide is expelled. Cool. Addexcess of sodium hydroxide and filter off the precipi-

tated manganese hydroxide, washing thoroughly. Thefiltrate containing the zinc in solution as sodium zincate

is acidified with hydrochloric acid, heated to about

80 C., and titrated with potassium ferrocyanide in the

usual manner.

Any barytes, silica, and insoluble silicates are sepa-

rated and estimated as usual.

CHAPTER XXIII.

ANALYSIS OF BLUE PIGMENTS AND PAINTS.

Analysis of Prussian Blues, Chinese Blues, etc.

427. Hygroscopic moisture. Heat 2 grams to 105 C.

for 3 hours. Loss in weight represents hygroscopicmoisture.

428. Water of combination. The water of combination

(so called) cannot with advantage be determined

directly, but can be approximated by subtracting the

total per cent of constituents determined hygro-

scopic moisture, cyanogen, iron, aluminum, alkali

metal, alkaline sulphate, and inert base, if any from

100 per cent.

429. Iron. Ignite 1 gram at a temperature sufficient

to decompose the last trace of the blue, but not so

high as to render the oxide of iron difficult of solution.

Dissolve in 25 c.c. of hydrochloric acid and 25 c.c. of

water with aid of heat. Filter, making up filtrate to

250 c.c. Titrate 50 c.c. with potassium permanganate,after adding stannous chloride, mercuric chloride, and

manganous sulphate solution in the usual manner.

Calculate to metallic iron.

430. Aluminum. Precipitate the iron and aluminum

from 50 c.c. of the iron solution. Filter, ignite, and

weigh, estimating the alumina by difference. It prob-

ably exists in the Prussian blue as aluminum ferrocy-

anide. Calculate to metallic aluminum.204

ANALYSIS OF BLUE PIGMENTS AND PAINTS. 205

431. Calcium. Calcium compounds are very rarely

found in Prussian blues. If the Prussian blue is pre-

cipitated on barytes, the latter is liable to contain a

small amount of calcium carbonate as an impurity.

Treat the filtrate from 430 with ammonium oxalate.

Settle, filter, ignite, and weigh as calcium oxide. Cal-

culate to calcium carbonate.

432. Alkali metal and alkaline salts. The filtrate from

431 is evaporated to dryness in a weighed evaporating

dish, the ammonium salts completely volatilized, the

alkaline salts weighed, and the chlorine therein deter-

mined by titration with standard silver nitrate solution.

The alkali metal is, almost without exception, entirely

sodium or potassium and not a mixture of the two, and

may be identified by the flame test, using a small frag-

ment of the weighed alkaline salt. The sulphuric acid

is estimated, in 50 c.c. of the solution, in the usual

manner. The amount obtained is calculated to sodium

sulphate or potassium sulphate, as the case may be.

The potassium or sodium chemically combined with

the Prussian blue is calculated from the amount of

chlorine found and reported as metallic sodium or

potassium.

433 Cyanogen. Estimate the nitrogen in 1 gram of

the sample by the Kjeldahl-Gunning method. Multiplythe nitrogen obtained by 1.86 to convert it into cyanogen.

434. Barytes, silica, clay, etc. The insoluble portion

remaining on the filter paper in 429 is ignited and

weighed. Fuse with sodium carbonate and estimate

the barytes, silica, alumina, etc., as described under

analysis of white paints.

435. Calculations. The amount of Prussian blue maybe calculated approximately by multiplying the iron

content by 3.03 or the nitrogen content by 4.4. These


factors are not exact, as Prussian blues have varying

compositions.A Prussian blue to be considered pure should contain

at least 20 per cent of nitrogen and 30 per cent of iron

calculated on the dry matter and after burning should

be entirely soluble in hydrochloric acid. A dry blue

should contain less than 7 per cent moisture, and the

sulphuric acid in the Kjeldahl nitrogen determination

should not be blackened, which \vould indicate organic

adulteration.

436. ANALYSES OF "PURE" PRUSSIAN BLUES.1

I. II. III. IV.

Moisture (lost at 100 C.) . 5.61 3.54 5.36 5.45Water of combination, etc. . 15.46 18.18 6.22 13.07

Cyanogen 37.72 41.10 42.97 37.90Iron 29.48 32.16 34.27 30.32Aluminum 1.82 .52 ... 3.17Alkali metal (Na) .... 7.60 (K) 4.50 (K) 7.72 (K) 2.25Alkaline sulphate .... 2.31 3.46 7.84

100.00 100.00 100.00 100.00

v. VI. VII. vm.Moisture (lost at 100 C.) . 74.53 5.32 5.56 5.61

Water of combination, etc. . 3.08 7.86 14.60 16.93

Cyanogen 10.64 39.91 40.19 40.86Iron 7.97 30.94 31.94 31.25

Aluminum 72 1.00 1.43 1.52

Alkali metal (Na) (K)1.06 (K)ll.31 Na2.52 .76

Alkaline sulphate 2.00 3.66 3.76 Na3.07

100.00 100.00 100.00 100.00

1Parry and Coste, The Analyst, Vol. XXL, page 227.

437. ANALYSES OF CHINESE BLUES BY AUTHOR.I. II. in.

Moisture (lost at 100 C.) 2.49 3.45 2.04

Water of combination, etc 12.69 18.12 8.75

Cyanogen .45.78 36.51 46.09

Iron 35.87 32.34 35.86

AluminumAlkali metal Nal.57 (K)4.89 Na3.80Alkaline sulphate 1.50 3.61 3.35

Silica 0.10 1.08 0.11

100.00 100.00 100.00


Analysis of Mixed Paints Containing Prussian Blue,

Chinese Blue, etc.

438. Weigh 1 gram into a 250 c.c. beaker, add 30 c.c.

of concentrated hydrochloric acid, boil 5 minutes, add

50 c.c. of hot water, boil 10 minutes, filter. Wash

thoroughly with boiling water. Ignite, filter, and pre-

cipitate gently, so as to destroy the blue color but not

at a sufficiently high temperature to render the iron

oxide difficultly soluble in acid. Cool, digest in moder-

ately concentrated hydrochloric acid until the iron is

all dissolved. Dilute, filter, adding this filtrate to the

first filtrate. The insoluble residue is ignited, weighed,

and fused with sodium carbonate, the barium, silica,

and alumina separated as described under analysis of

white paints. The lead, iron, soluble aluminum, zinc,

and any calcium and magnesium compounds separated

and estimated as described under analysis of mixed

paints containing blacks and oxide of iron pigments.

439. If the paint in question is free from other iron

pigments, the percentage of Prussian blue may be cal-

culated by multiplying the iron content by 3.03. If

other iron pigments are present the nitrogen content

must be determined; this multiplied by 4.4 will give the

approximate amount of Prussian blue present.

Analysis of Ultramarine.

440. Properties. Ultramarine is a compound of silica

containing alumina, soda, sulphur, and combined sul-

phuric acid. It has been often stated that ultramarine

cannot be mixed with white lead, because of the sul-

phur content of the ultramarine, but the author has

ascertained that a great many paint manufacturers


use it in tinting mixed paints where the percentage of

white lead does not exceed that of the zinc, without anyharmful results following. Ultramarines that are to be

used in the manufacture of paper should be tested for

their power of resisting the action of alum, by boiling

5 grams in a 5 per cent alum solution. As found on

the market, ultramarines vary much in tint, brilliance,

and coloring power.

441. Moisture. Heat 2 grams at 1.05 C. for 3 hours,

cool, and weigh.

442. Silica. Digest 1 gram in a casserole providedwith a beaker cover, with 30 c.c. of concentrated hydro-chloric acid. Evaporate to complete dryness, cool, add

2 c.c. of concentrated hydrochloric acid, evaporate to

dryness, and heat gently for 15 minutes. Take up in

100 c.c. of hot water, add 10 c.c. of hydrochloric acid.

Filter, ignite, and weigh as silica.

443. Alumina. The nitrate from the silica is made just

sufficiently alkaline with ammonia to precipitate the

aluminum. Heat gently, filter, ignite, and weigh as

alumina.

444. Sodium oxide. The filtrate from the alumina is

neutralized with sulphuric acid in a porcelain evaporat-

ing dish, evaporated to dryness, the residue treated

with a little sulphuric acid, evaporated to dryness

again, treated with water, evaporated to dryness, and

ignited at low red heat, cooled, and weighed.

Wt. sodium sulphate X 0.4366 = wt. of sodium oxide.

445. Total sulphur. Fuse 1 gram in a large crucible

with a mixture of potassium nitrate and potassiumchlorate for about half an hour. Dissolve the fused

mass in dilute hydrochloric acid and boil the solution

with strong nitric acid for half an hour, filter off the


silica and precipitate the sulphuric acid with barium

chloride in the usual manner. Filter, ignite, and weighas barium sulphate.

From the weight of barium sulphate thus obtained

deduct the weight found in 446; the difference is the

amount due to sulphur present in the blue as sulphide.

Wt. barium sulphate X 0.1373 = wt. sulphur.

446. Combined sulphuric acid. Dissolve 1 gram in

dilute hydrochloric acid. Filter off the silica, makefiltrate alkaline with ammonia and then just distinctly

acid with hydrochloric acid, and treat with barium

chloride in the usual manner. The precipitated barium

sulphate is filtered, ignited, and weighed as usual.

Wt. barium sulphate X 0.3434 = wt. of sulphur tri-

oxide.

447. ANALYSES OF ULTRAMARINES BY THE AUTHOR.Ultra-marineBlue.

I.

Silica 39.26Alumina 25.60

Sulphur -11.69

Sulphur trioxide .......... 3 . 10Sodium oxide 19 . 87Water 0.48

100.00 100.00 100.00

448. ANALYSES OF ULTRAMARINES BY HURST.

SnlnhatP Soap Calico PaperSulphate. Makers. Printers. Makera.

Silica 49.69 40.65 40.89 45.42Alumina 23.00 25.05 24.11 21.15Sulphur 9.23 12.95 13.74 11.62Sulphur trioxide 2.46 4.81 3.05 5.58Soda ..-V. . . 12.49 14.26 15.61 9.91Water . 3.13 2.28 2.60 6.32

100.00 100.00 100.00 100.00


Analysis of Cobalt Blue.

449. This pigment, which is essentially a compound of

the oxides of alumina and cobalt, has largely gone out of

use, but that.it still finds a limited application is evi-

denced by the fact that the author receives occasionally

samples for analysis. Certain shades of ultramarine

blue are often sold under the name of cobalt blue.

450. Moisture. Determine as usual.

451. Alumina. Fuse 1 gram with potassium bisulphate

as described under analysis of Indian reds and Venetian

reds. Dissolve in water and hydrochloric acid, filter,

and make up to 250 c.c. in a graduated flask. Anyresidue remaining on the filter paper is ignited and

weighed as silica, unless barium sulphate is present,

which would be shown by the flame test.

An aliquot portion of the solution is treated with an

excess of ammonium chloride, and then made just dis-

tinctly alkaline with ammonia. Filter, dissolve on the

filter with hydrochloric acid, and reprecipitate. Filter

again, combining the twt> filtrates. Wash thoroughly,

ignite, and weigh as alumina.

452. Calcium and magnesium. The combined filtrates

from the alumina are saturated with hydrogen sulphide,

filtered, and any calcium and magnesium estimated in

the filtrate in the usual manner.

453. Cobalt oxides. The oxides of cobalt present are

best estimated by difference, by subtracting the deter-

mined constituents from 100. It is stated by Hurst

that phosphoric acid is occasionally used in the manu-facture of cobalt blues, in which case it should be re-

moved before estimating the aluminum, calcium, and

magnesium. The several samples examined by the

author were found to be free from phosphoric acid.

CHAPTER XXIV.

ANALYSIS OF YELLOW, ORANGE, AND RED CHROMELEADS; ANALYSIS OF VERMILIONS.

454. Composition. The lemon yellow chromes usuallycontain sulphate of lead, sometimes carbonate of lead.

The red chromes, known by the various names of scarlet

chrome, chrome red, Chinese red, American vermilion,

and vermilion substitute, may be considered as basic

chromates of lead. Often these basic chromes are

brightened, up by having precipitated on them an

organic color; this may be tested for by treating a por-

tion of the pigment with alcohol, which will dissolve the

organic color, giving a strongly colored solution. See

analysis of vermilions.

455- Hygroscopic moisture. Heat 2 grams at 105 C.

for 3 hours. Loss in weight represents hygroscopicmoisture.

456. Barytes, silica, and clay. One gram of the pig-

ment is boiled for 5 minutes with 30 c.c. of concen-

trated hydrochloric acid in a covered beaker. While

boiling add half a dozen drops of alcohol one at a time.

Fifty c.c. of water is added and the boiling continued

for 10 or 15 minutes. Filter, wash thoroughly with

boiling water, ignite, and weigh. The insoluble resi-

due is fused with sodium carbonate, and the barium,

silica, and alumina separated as described under analysis

of white paints.

457. Lead. The filtrate from the insoluble residue is

neutralized with dilute ammonia until the further addi-211


tion of another drop would cause the formation of a per-

manent precipitate, diluted to about 250 c.c. to 300 c.c.,

and hydrogen sulphide passed in for 10 minutes.

Solutions containing large amounts of chromium, if

neutralized with ammonia until a permanent precipi-

tate appears, seem to require an excess of hydrochloric

acid for their resolution, sufficient to prevent the satis-

factory precipitation of the lead with the hydrogen

sulphide.

Allow the precipitate to settle thoroughly, as it ren-

ders the filtering much easier, filter, wash with hydrogen

sulphide water. Boil, filter, and precipitate with dilute

nitric acid, until all of the lead has dissolved, filter with

aid of suction, washing thoroughly with hot water.

Add 5 c.c. of concentrated sulphuric acid, diluted with

an equal volume of water, to the filtrate. Evaporateon hot plate until the white fumes of sulphur trioxide

appear. Cool, dilute with water, add an equal volume

of alcohol, filter, washing with dilute alcohol, ignite

gently, and weigh as lead sulphate. Save filtrate.

458. Chromium. The alcoholic filtrate from the lead

sulphate is evaporated nearly to dryness to expel alco-

hol, and the filtrate from the lead sulphide heated until

the hydrogen sulphide is expelled. The two filtrates

are mixed, diluted if necessary, and made just percep-

tibly alkaline with ammonia; boil, settle, filter, wash

thoroughly, ignite, and weigh as chromic oxide.

Wt. chromic oxide X 1.3137 = wt. chromic anhy-dride.

Occasionally these pigments contain a small quan-

tity of iron, which should be tested for qualitatively

in a separate portion of the pigment. If found to be

present, the precipitate of ferric and chromium hydrox-ides is dissolved on the filter with hydrochloric acid,

ANALYSIS OF CHROME YELLOW, ETC. 213

the filter washed thoroughly with hot water, and the

iron and chromium in the filtrate reprecipitated with

ammonia and treated with sodium peroxide to dis-

solve the chromium as described under the analysis

of chrome greens.

459. Calcium. The filtrate from the chromium is

treated with ammonium oxalate, allowed to stand in a

warm place for an hour or so, filtered, washed thor-

oughly, strongly ignited, and weighed as calcium oxide.

460. Magnesium. The magnesium is estimated in

the filtrate from the calcium in the usual manner.

461. Combined sulphuric acid. The combined sulphuric

acid may be estimated by either of the two methods

given in the chapter devoted to the analysis of white

paints. In fact, the latter method may be used for

the rapid analysis of a chrome lead, the insoluble lead

carbonate being filtered off, the chromium precipitated

as the hydroxide in the usual manner, and the com-

bined sulphuric acid estimated in the filtrate from the

chromium.

Wt. barium sulphate X 0.3433 = combined sulphu-

ric acid.

462. Calculations. If calcium is absent, or present as

carbonate, the combined sulphuric acid is calculated to

lead sulphate, the chromic anhydride to lead chromate,and excess of lead to lead oxide. If calcium sulphate

and carbonate of lead are present, the carbon dioxide

must be determined and the amount of calcium present

as sulphate estimated by Thompson's method as de-

scribed under analysis of white paints.

Wt. comb, sulphuric acid X 3.788 = wt. lead sul-

phate.

Wt. chromic anhydride X 3.230 = wt. lead chro-

mate.


Wt. lead chromate X 0.6406 = wt. lead.

Wt. lead X 1.0773 = wt. lead oxide.

The specifications for chrome leads issued by the U. S.

Treasury Department, 1907, state that a color contain-

ing lead sulphate is to be preferred to one containing

white lead.

463. ANALYSES OF CHROME LEADS BY AUTHOR.

. I * HMoisture 0.04 0.03Lead chromate 68.65 40.56Lead oxide

'

47.24Lead sulphate 31.21 5.49Silica 0.74Alumina , . ... . 44

Organic color ... 4 . 87Undetermined . 0.10 0.63

100.00 100.00

Analysis of Mixed Paints Containing Chrome Yellows

and Ochres.

464. Barytes, silica, and clay are estimated as described

under analysis of chrome leads.

465. Lead, both as sulphate and carbonate, is esti-

mated as described under chrome leads, the filtrate

from the lead sulphate being saved as before.

466. Iron. The filtrate from the lead sulphide is heated

until all of the hydrogen sulphide has been expelled and

added to the filtrate from the lead sulphate from which

the alcohol has been expelled by boiling. A few dropsof nitric acid are added and the solution boiled for a

minute or two, then made just distinctly alkaline with

ammonia, boiled, settled, and filtered.

Dissolve on the filter with hot dilute hydrochloric

acid, wash with hot water. Cool. Reprecipitate with


ammonia, avoiding excess, without waiting for the pre-

cipitate to settle, carefully add a sufficient quantity of

sodium peroxide (1 gram is usually sufficient), keepingthe beaker covered meanwhile. Digest until all of the

chromium and aluminum have passed into solution,

adding more peroxide if necessary. The iron remains

undissolved, while the chromium and aluminum go into

solution; filter, wash thoroughly, ignite strongly, and

weigh as ferric oxide, or dissolve in dilute hydrochloric

acid and titrate. The treatment with peroxide is pref-

erably performed in a porcelain evaporating dish.

467. Chromium. The nitrate from the iron is made upto 250 c.c. in a graduated flask. An aliquot portion is

rendered acid with acetic acid and a slight excess of

lead nitrate solution added, allowed to remain on the

hot plate until thoroughly settled, filtered onto a

weighed Gooch crucible, washed, dried, and weighed as

lead chromate.

468. Aluminum. An aliquot portion of the 250 c.c.

solution is made just acid with hydrochloric acid, andthen just distinctly alkaline with ammonia, allowed to

settle, filtered onto a Gooch crucible, ignited, and

weighed as alumina.

469. Zinc. The filtrate from the chromium, iron andaluminum hydroxides, under iron is mixed with the fil-

trate from the lead sulphate from which the alcohol

has been expelled, and the mixed solution saturated

thoroughly with hydrogen sulphide, boiled with the

addition of solid ammonium chloride to render the pre-

cipitate less slimy, and filtered. The zinc sulphidedissolved with hydrochloric acid, boiled to expel hydro-

gen sulphide, and titrated with standard ferrocyanideof potassium as described under analysis of white

paints.


470. Calcium, magnesium, and combined sulphuric acid

are estimated as described under analysis of chrome

leads and the calculations made as there described.

Analysis of Vermilion.

471. Properties. Vermilion is a bluish scarlet powder,

having a specific gravity of 8.2. It is insoluble in anysingle acid such as hydrochloric or nitric acid and in

the alkalies. Heated in contact with the air, it burns

with a pale blue lambent flame. Pure vermilion will

burn away entirely or at least leave but a small fraction

of 1 per cent of ash. This is a reliable test for it, as

other adulterants would be left behind on heating.

The most common adulterants of vermilion are red

lead, oxide of iron, lead chromes, vermilionette lakes,

para reds, and alizarine reds.

472. Detection of vermilionettes, para and alizarine

reds, (a) . Boil a little of the dry color with water, set-

tle, and filter. Vermilionettes give a deep red solution,

para reds a pale brownish or orange, and the alizarine

reds a colorless solution.

(6). Boil a little of the dry color with a mixture of

methyl and ethyl alcohol, filter, heat, and settle. Ver-

milionettes give a bright red solution, usually havinga yellow "bloom," para reds an orange-red solution,

alizarine reds a practically colorless solution.

(c). Boil another portion of the dry pigment with

some freshly distilled aniline, settle, and filter. Ver-

milionettes give a purple-red, alizarine lakes a pale

brown, and the para reds an intense orange-red solu-

tion.

(d). Boil some of the dry color with a solution of

caustic soda. Vermilionettes give a red solution with


a green "bloom," para reds a bluish red solution,

while alizarine reds yield a characteristic deep violet

solution.

473. Barytes, silica, and clay. Dissolve 1 gram in 30

c.c. of concentrated hydrochloric acid, 50 c.c. of water

with the aid of 1 to 2 grams of potassium chlorate added

in small portions and warming. Evaporate to dryness

on water bath. Take up in 50 c.c. of water acidulated

with hydrochloric acid, heat to boiling to dissolve anylead chloride, filter, wash with boiling water, ignite, and

weigh any insoluble residue. Fuse with sodium carbon-

ate and estimate the barium sulphate, silica, and alu-

mina as described under analysis of white paints.

474. Lead. If lead is present, calcium compounds

being absent, the filtrate is treated with sulphuric acid,

evaporated carefully to expel excess of hydrochloric

acid, diluted with water and alcohol, the lead sul-

phate filtered off on a Gooch crucible in the usual

manner.

475. Mercuric sulphide (vermilion). The filtrate from

the insoluble residue, if lead is absent, or the filtrate

from the lead sulphate, is heated with a little sulphur-

ous acid to reduce any iron present to the ferrous con-

dition, made neutral with ammonia, and then just acid

to litmus with hydrochloric acid.

The solution is diluted to about 350 c.c. and hydro-

gen sulphide passed in for 10 minutes. The mercuric sul-

phide is filtered off on a weighed Gooch crucible, washed

with hydrogen sulphide water, the crucible removed to

another holder and washed with alcohol and carbon

bisulphide to remove sulphur, dried in steam oven, and

weighed.

476. Estimation of lead and mercury, calcium com-

pounds present. The filtrate from the insoluble residue


from 473 is precipitated with hydrogen sulphide as de-

scribed under 475, collected on a weighed filter, and

dried at 100 C., weighed, and mixed uniformly.An aliquot part is introduced into the bulb of Fig. 10,

a slow stream of washed chlorine gas passed through it,

FIG. 10.

and a gentle heat applied to the bulb, increasing this

gradually to faint redness. The escaping chlorine is

conducted into a flue. First, sulphur chloride distills

over, which decomposes with the water in E and F.

The mercuric chloride formed volatilizes, condensing

partly in E, partly in 0. Cut off that part of the tube,

rinse the mercuric chloride into E, and mix the contents

of the latter with the water in F. Mix the solution

with excess of ammonia and warm gently until no more

nitrogen is evolved, acidify with hydrochloric acid, fil-

ter, and determine the mercury in the filtrate as under

475.

477. Ferric oxide. The filtrate from the sulphides is

heated until all of the hydrogen sulphide has been ex-

pelled and the iron chromium and alumina precipitated

with ammonia, filtered and separated as described under

analysis of chrome greens.


478. Zinc oxide. The filtrate from the iron and alu-

mina precipitate is made distinctly alkaline with am-

monia and the zinc precipitated with hydrogen sulphide.

The liquid containing the zinc sulphide precipitate is

heated to boiling, and about 5 grams of solid ammoniumchloride added, which renders the precipitate easier

to filter. Settle, filter, wash thoroughly. Pierce filter,

wash through into a clean beaker with water, dissolv-

ing the residue on filter with dilute hydrochloric acid,

and washing with hot water. Dilute, heat to expel

hydrogen sulphide, and titrate with ferrocyanide as pre-

viously described. If iron is absent in the paint, the

zinc may be estimated directly as described under

analysis of white pigments.

479. Calcium and magnesium. Estimated as usual in

the filtrate from the zinc sulphide.

480. Calculations. If chromium is present it is cal-

culated to basic lead chromate, and any excess of lead

above that required to form the chromate is calculated

to red lead.

481. ANALYSES OF VERMILIONS BY THE AUTHOR.I. II. ill.

English EnglishVermilion. Vermilion. Vermilion.

Deep. Pale.

Sulphide of mercury .... 99.53 99.61 99.61Ash 0.47 0.39 0.39

100.00 100.00 100.00

I. II.

, RadiumVermilion. ,.. ...

Vermilion.

Moisture 0.16 0.06Red lead 80.08 97.99

Barytes 16.83Alumina . 77

Organic color 2.16 1.95

100.00 100.00


100.00 100.00

482. Antimony vermilion and orange. These two pig-

ments have the same composition, corresponding to the

formula of antimony trisulphide. They are insoluble

in dilute acids, but soluble in strong hydrochloric acid.

It is seldom necessary to make a complete analysis of

these pigments. Adulteration will be indicated by the

pigment not being completely soluble in strong hydro-

chloric, though a trace of sulphur may remain undis-

solved, floating on top of the acid.

CHAPTER XXV.

ANALYSIS OF RED LEAD, ORANGE MINERAL, ANDLITHARGE.

483. Red lead. This pigment, corresponding to the

formula Pb3 4 ,is prepared by three different processes :

1. The dressing process, in which a puddle of molten

lead is slowly drossed in a reverberatory furnace by con-

stant rabbling, and the dross or massicot thus obtained

is water ground and floated to free from metal particles

and calcined for about 48 hours at a definite tempera-ture in another reverberatory furnace. The product is

usually bolted through a silk bolting cloth.

2. The nitrate process, in which metallic lead and

nitrate of soda are fused together, yielding an oxide of

lead (PbO) and nitrite of soda (NaN02). This oxide,

after having been thoroughly leached to remove the

nitrite, is calcined and finished as above described.

The nitrite of soda obtained by this process has a

large use in the manufacture of para reds. Red lead

manufactured by this process will usually contain a

small amount of caustic soda and nitrite of soda.

3. The basic oxide process, in which molten lead is

Very finely subdivided by superheated steam, con-

verted into a basic oxide by agitation with air and

water, dried, ground, and calcined for about 15 hours,

which is sufficient to develop the full color. This proc-

ess represents the latest and most advanced stage of

oxide manufacture, yielding for many purposes a much

superior product.221


484. A thorough physical examination of red lead is

of fully as much importance as a chemical analysis.

485. Microscopical examination. Under the micro-

scope the red lead should show freedom from metallic

particles, vitrified red-lead particles, and foreign matter

such as coal dust, furnace grit, etc.

486. Fineness. Less than one-tenth of 1 per cent

should be retained on a screen composed of number 20

or 21 silk bolting cloth.

487. Color. The color of red lead, as of the chrome

leads, depends on the size of the particles: the larger

the particles the deeper the tone, and the smaller the

particles the paler the color but with a marked in-

crease of fire and brilliancy. For the manufacture of

reduced red leads and of vermilions the deep tones are

the most desirable, as they require less dye.

488. Bulking figure. Hitherto, the great objection

to the use of red lead for painting structural] iron and

steel work has been its excessive tendency to settle in

the paint pot, preventing uniform application and a

manifest sagging and streaking. This is due both to

the density and the comparative large size of the red-

lead particles as compared with other well-known pig-

ments. The first two processes above described producea red lead having these characteristics, while the third

affords a very soft, bulky, amorphous red lead, the

particles of which are of a very uniform fineness. In

fact, red lead made by this process much resembles

orange mineral, having considerable fire and brilliancy,

and does not readily settle in the paint pot or sag on

vertical surfaces.

Other factors being equal, the bulkiest or least dense

red lead is the most desirable for painting purposes.

Red leads made by the first two processes give a bulking

ANALYSIS OF RED LEAD, ORANGE MINERAL, ETC. 223

figure of from 23 grams to 32 grams per cubic inch bythe Scott volumeter.

489. If a liberal percentage of carbonate tailings

from the Dutch process of white-lead manufacture has

been used, the bulking figure may go as low as 20 grams.

The third process yields a red lead having a bulking

figure of 15 grams to 18 grams. The writer firmly be-

lieves that users of red lead would secure a much in-

creased service value if they would specify a red lead

having a bulking figure of 20 grams or under.

490. Painting test. When mixed with pure linseed

oil, pure turpentine and Japan drier as per the U. S.

Navy Department formula (1909), viz:

Red lead, dry 17 poundsRaw linseed oil 4| pints

Spirits of turpentine 1 gill

Japan drier 1 gill

and applied to a smooth, vertical iron surface, it must

dry solidly without running, streaking, or sagging. It

should be noted that while this formula affords a goodtest for red leads of a moderate bulking figure, it

affords a mix entirely too thick with a red lead havinga bulking figure of 15 grams to 18 grams.

491. Free Litharge. The free litharge content of red

lead is a rather variable quantity; it may go as high as

25 per cent or as low as 1 per cent, the average being

perhaps between 6 and 12 per cent. No absolutely sat-

isfactory method has yet been devised for its determina-

tion. The acetate method is probably as satisfactory

as any.

492. Weigh 10 grams of the sample into a 150 c.c.

beaker provided with a cover glass, add 25 c.c. of a

neutral normal solution of acetate of lead and 50 c.c.

of freshly boiled distilled water. Boil gently for ex-


actly 5 minutes. Decant onto a Gooch crucible, wash

by decantation with boiling water twice, collect residue

on crucible, and wash thoroughly with boiling water,

then with a few drops of alcohol dry in steam oven,

cool, and weigh. The weight of the residue subtracted

from 10 indicates the amount of free litharge present.

The government specifications require at least 94 per

cent true red-lead content, which insures a litharge con-

tent of 6 per cent or less.

493. Peroxide content. Numerous methods have been

devised for determining the peroxide content of red

lead. Mannhardt's method is perhaps the most accu-

rate.

Weigh out 1 gram of the pigment. Triturate this

with 1.176 grams of ammonium ferrous sulphate crys-

tals. 0.1176 gram of the salt corresponds to 1 c.c. of

3 N-10 (oxidizing) solution and to .03585 Pb02 . Thetrituration is carried out carefully. The mixture is

then brushed into a small beaker and about 10 gramscommercial ammonium chloride added. This is mois-

tened and the pigment stirred in and 20 c.c. of water

and 20 c.c. of hydrochloric acid added. The mixture

is warmed on the steam plate and then titrated for

excess of ferrous iron with a 3 N-10 oxidizing solution of

bichromate (29.5 grams to 2 liters), using a pale yellow

solution of potassium ferrocyanide as external indicator.

The ferrous solution must be very strongly acid when

nearing the endpoint, in order to obtain a very definite

endpoint.

The weight of ferrous ammonium sulphate used in

the determination of the peroxide should be about

5 per cent in excess of the theoretical consumption.The range of consumption of ferrous salt will vary

between 7 c.c. and 9.6 c.c. of the bichromate solution.

ANALYSIS OF RED LEAD, ORANGE MINERAL, ETC. 225

494. Orange mineral. This product may be consid-

ered as a debased form of red lead, inasmuch as it is

not so stable toward light as red lead. It is usually

prepared by calcining white-lead residues or tailings.

Its specific gravity is much lower than that of red lead.

It may be differentiated from red lead by microscopical

examination. Under a magnification of 400 to 500

diameters the particles of red lead much resemble small

crystals of bichromate, being distinctly transparent,

while orange-mineral particles are much smaller and

quite opaque.

495. The same physical and chemical determinations

that apply to red lead apply to orange mineral. The

litharge content of orange mineral is usually very low,

and for this reason it is often ground in linseed oil and

put on the market in paste form, whereas the higher

litharge content of red lead would cause "livering"

and hardening in the package except in occasional in-

stances when a very carefully selected red lead is used.

496. Litharge. The different brands of litharge found

on the market will vary greatly in color and other physi-

cal characteristics, which are determined by the prefer-

ence of the buyer. The three leading impurities which

are of interest to the paint chemist are metallic lead, sul-

phates, and red lead, all three usually being classed to-

gether as' '

insoluble matter.' ' The metallic lead and red

lead are particularly objectionable to the color maker,as they affect the purity of the tint of his colors, theynot being soluble in acetic acid. The insoluble matter

may be determined by boiling 5 grams of the samplewith dilute acetic acid, filtering onto a Gooch crucible,

washing thoroughly with hot water, drying, and weigh-

ing. The insoluble matter should not exceed 0.6 percent.


497. Carbon dioxide. Freshly prepared litharge is

free from combined carbon dioxide, as the temperature

at which it is furnaced is more than sufficient to de-

compose any carbonate of lead that might be present.

On exposure to air, however, litharge absorbs carbon

dioxide in notable quantities. This is especially true of

samples of litharge sent by mail in paper envelopes or

of samples allowed to remain in the laboratory. The

determination of carbon dioxide can be made in the

usual manner, although the shipment of goods in bulk

will usually show practically entire absence of carbon

dioxide.

498. Sulphates. The commercial grades of litharge

will contain a small fraction of 1 per cent of sulphate of

lead, due to the sulphur gases from the coal used in the

furnacing. The sulphate content can be determined

as stated in the chapter devoted to the analysis of

white lead. The small quantity usually found is not

objectionable for dry-color manufacture, as it under-

goes conversion with the chromates used and therefore

may be deducted from the total insoluble matter, thus

affording the percentage of distinctly objectionable im-

purities, viz., metallic lead and red lead.

CHAPTER XXVI.

ANALYSIS OF PAINTS FOR MANUFACTURING PURPOSES.

499. Classification. Under the above heading is in-

cluded an immense variety of paint products, the ma-

jority of which are sold in paste or semi-paste form, the

thinning down being accomplished by the purchaser.

The most common use is for agricultural machinery,such as harvesters, threshers, wagons, plows, etc., the

paint usually being applied by the"dipping" process.

A large amount of paints is used for bedsteads, refrig-

erators, etc. Considerable amounts of paint are used

in the manufacture of toys, as primers for sashes and

doors, for shade cloth, oilcloth, trunks, etc. Bridge

paints, structural iron and steel paints, and paints for

the railroad trade also form a very important class of

paint products.

500. Analysis. The analysis of these various paint

products offers no particular difficulties, and the schemes

outlined in other chapters for the various colors will be

found to be satisfactory in the majority of instances.

Immense quantities of para reds, precipitated on vari-

ous inert bases such as barytes, china clay, magne-'sium silicate, etc., are used in agricultural paints. Theactual amount of para red used is the most importantfactor in determining the cost or selling price of such

paints. The amount present can be determined ap-

proximately by difference, i.e., by determining the

combined percentage of inert materials and subtracting

from 100. Unless the determinations are performed227


with extreme care and discrimination, serious errors

are liable to be made, and it is often advisable to check

the analysis by a determination of the amount of parared present, which can be accomplished by determiningthe percentage of nitrogen by the Kjeldahl method,modified as for nitrates, as the diazo radical is so easily

broken down that unless considerable care is observed

a loss of nitrogen compounds will occur. The Kjeldahlmethod is given in full in the various published reports

of the Association of Official Agricultural Chemists.

501. Presence of color lakes. If the color of the paint

varies materially from that obtained with a straight

para red, other organic colors, as eosine, Bordeaux B,

Scarlet No. 1, etc.,, may be present, in which case the

nitrogen determination is to a large extent valueless.

For the detection of the different organic colors present

the author has found the"Treatise on Color Manu-

facture," by Zerr, Rubencamp and Mayer, the most

thorough and comprehensive of any yet published.

It should be remembered that while the principles

underlying the manufacture of the para reds, so called,

are well known, yet certain color makers are enabled

to produce more brilliant and stronger reds than others;

and in attempting to duplicate a manufacturing trade's

paint containing a para red the question of inherent

strength and brilliancy must be taken into considera-

tion.

502. Analyses. The following analyses made in the

author's laboratory show some of the combinations in

use by the leading manufacturers of agricultural ma-

chinery implements, shade cloth, beds, etc.

PAINTS FOR MANUFACTURING PURPOSES. 229

VERMILION PRIMERS.

I. II. III.

w Seeding Ma- HarvesterT> ,. TT* chinery. Machinery.

!ent<Per cent. Per cent.

White lead . . . 25.24Zinc-lead white 27.86

Lithopone '. ... 60 . 62Barium sulphate 5 . 80 15 . 18Barium carbonate ... 52 . 74Calcium carbonate 66.97 ... 36.80Iron oxide ... ... 1 . 25Para red. 1.99 4.22 1.33

100.00 100.00 100.00

PRIMING ENAMEL BEDS.

I. II.

Per cent. Per cent.

Lithopone 49.04 63.37Zinc oxide 2.60 22.50Calcium carbonate 48.27 13.85

99.91 99.72

WHITE BARREL PASTE.Per cent.

Zinc oxide 39.85Calcium carbonate 60 . 15

100.00

SHADE CLOTH, BODY WHITE.

Per cent.

Lithopone 33.21Silica 1.98Calcium carbonate 64 . 51

99.70-*

YELLOW AND GREEN PASTES PLOWS, WAGONS, PUMPS,PLANTING MACHINERY, ETC.

I. n.

Wagon Primer. Wagon Finish-

Percent -

PeV^ent

Leadchromate 10.75 34.00Calcium carbonate 47.60 66.00Barium sulphate 41 . 65

100.00 100.00


YELLOW AND GREEN PASTES PLOWS, WAGONS, PUMPS,PLANTING MACHINERY, ETC. Continued.

Lead chromate . .

White lead. . . .

Zinc oxide ....Calcium carbonate

I.

YellowWagonPaste.

Per cent.

8.3265.7013.2012.78

100.00

II.

YellowPumpPaste.

Per cent.

50.22

49.78

100.00

III.

YellowWagonPaste.

Per cent.

12.09

58.3529.39

99.83

CREAM PASTE HARVESTER.

Lithppone ....Calcium carbonateOchreChrome yellow . .

Per cent.

48.6448.791.081.49

100.00

Chrome green . .

Zinc oxide ....Barium sulphate .

Calcium carbonateAluminum silicate

I.

GreenPasteFarm

Machinery.Per cent.

2.8336.898.6751.61

II.

GreenPasteWagon.Per cent.

20.01

39 .'85

100.00 100.00

I.

Green PlowPaste.

Per cent.

Chrome green 5 . 00Zinc lead 58.51Barium sulphate 13 . 70Calcium carbonate . 22 . 79

100.00

II.

Green PlowPaste.

Per cent.

4.92

10.5784.51

100.00

PAINTS FOR MANUFACTURING PURPOSES. 231

RED WAGON PASTES.

I.

Per cent.

Zinc oxide 12.05Barium sulphate 42 . 00Calcium carbonate 30 . 09Aluminum silicate ...

Red lead . . . .

Para lake 15.86

100.00

II.

Per cent.

87.522.45

l6! 03

100.00

III.

Per cent.

7.3537.80

44.4410.41

100.00

IV.Per cent.

Barium sulphate 50 . 25Red lead 41.26Calcium carbonate ...

Para lake . . . 8.49 1

100.001 Includes eosine.

v.Per cent.

43.6551.384.97 1

100.00

VI.Per cent.

9.5262.7823.664.04

100.00

RED LADDER PASTE.Per cent.

Barium sulphate 72.37Red lead 20.28Para lake 7.35

100.00

RED PLOW PASTE.Per cent.

Zinc oxide 11.15Barium sulphate 44 . 35Calcium carbonate 30 . 68Para lake 13.82

100.00

RED THRESHER PASTE.Per cent.

Zinc oxide 9 . 95Barium sulphate 53 . 45Calcium carbonate . 20.20Para lake 16.40

100.00


RED SEEDING MACHINERY PASTE.Per cent.

Barium sulphate . 17.10Calcium carbonate 63 . 58Red lead 12.80Para lake 6.52

100.00

503. Dipping paints. As previously stated, a large

portion of the agricultural machinery and implement

paints is applied by what is known as the dipping proc-

ess, i.e., the articles to be painted are dipped in large

tanks of the thinned paint. It is obviously necessarythat the pigments used should be carefully and thor-

oughly ground and of as non-settling a nature as pos-

sible. These features are of as much importance as

the chemical composition.

CHAPTER XXVII.

COMPOSITION AND ANALYSIS OF FILLERS.

504. Under the heading of fillers are included paste

and liquid wood fillers, crack and crevice fillers, iron

fillers, and rough stuff. The composition and proper-

ties of these various fillers will be considered separately.

505. Wood fillers. The fact that many of the woodfillers on the market are of inferior quality is not due

to lack of knowledge of the manufacturer but to the

question of price. The pigment portion of a high-grade

paste wood filler should consist of 70 to 80 per cent of a

finely ground quartz, such as Bridgeport silica, which

possesses a decided"tooth." The remaining portion,

30 to 20 per cent, may be a "toothless" silicate like the

well-known F. S. A. silica. The addition of 1 to 2 per

cent of powdered starch is also of material benefit.

The vehicle should be composed of a good medium-

drying oil Japan, raw linseed oil, and turpentine; water

should be absent.

The cheapening of wood fillers is accomplished byusing an inferior benzine-rosin Japan and a cheap white

silicate in place of the crushed quartz silica, the former'

being obtained at about one-third of the cost of the

latter. Sometimes white mineral primer may be added

for cheapening. Besides the customary chemical an-

alysis, a careful microscopic examination should be

made in order to differentiate the silicas used, the

crushed quartz silica being recognized by the charac-

teristic wedge-shaped structure of the particles; the233


fineness of the particles being regulated according to the

nature of the wood to be filled, open-grained woods re-

quiring a filler containing quite a percentage of com-

paratively coarse particles.

506. Tinted wood fillers contain small percentagesof tinting colors such as ochre, bone black, burnt umber,

Vandyke brown; golden oak being obtained with the

aid of ochre, burnt umber, and Vandyke brown; light

oak with the use of a little ochre only; dark and light

antique with the aid of burnt umber; and walnut with

the aid of an asphaltum black.

507. Transparent liquid wood fillers or surfacers for

hard, close-grained woods usually contain only 16 to

20 per cent of pigment, which may be white filler

(talcum), or better, a mixture of crushed quartz silex

and white filler. The vehicle should be a light, quick,

hard-drying kauri varnish with turpentine thinner.

Kerosene-oil-and-water emulsions have no legitimate

place in this class of goods, although often present.

Instead of kauri varnish, a rosin-china wood-oil var-

nish is often used, but is apt to cause considerable

trouble, as on sandpapering it will either dust or soften

and roll up under the paper.

508. Crack and crevice fillers. The basis of this class

of goods is usually powdered starch, raw linseed oil,

benzine Japan, and naphtha, which affords a cheap,

efficient paste for the purpose indicated.

The following formula is typical of this class of

products :

Starch 100 Ibs.

Raw linseed oil 3f gal.

Benzine drier H gal.Benzine 1| gal.

509. Iron fillers. This class of paints is always sold

in paste form and may contain a small percentage of

COMPOSITION AND ANALYSIS OF FILLERS. 235

white lead or zinc lead, Keystone filler, white filler,

silica, barytes, or white mineral primer ground in lin-

seed oil and Japan. The low price at which these

fillers are sold, 3 to 4 cents per pound, precludes the

use of any large percentage of lead pigments.

510. Analyses. The following analyses indicate the

nature of some of the iron fillers on the market :

i. n. m.White. Black. Maroon.


Barium sulphate 40.85 ... 37.40White lead 16.12 5.26Calcium carbonate 43 . 03

Keystone filler 94.74Ferric oxide ... 30.51 1

Silica and silicates ... 12. 97 1

Calcium sulphate, hydrated ... ... ... 19.12

100.00 100.00 100.001Evidently Princes' metallic and Indian red.

The vehicles were judged to be blends of grinding

Japan, rosin-china wood-oil varnish, and a benzine drier.

511. Rough stuff. This product is somewhat similar

to iron filler in composition, but it usually has a much

higher lead content and therefore commands a better

price. The pigment portion is usually white lead, Key-stone or similar filler, and a small percentage of lamp-

black, bone black, or carbon black. The vehicle is also

similar to that used in iron fillers, except that in the

better class of rough stuff a fairly good grade of kauri

varnish is used.

ANALYSES OF ROUGH STUFF.I. n.

Per cent. Per cent.

Keystone filler 73.18 1 76.24 2

White lead. 26.82 23.76

100.00 100.00

1 Tint indicated presence of small amount of lampblack.2 Contained considerable magnesium silicate; white filler probably

present.

CHAPTER XXVIII.

SHINGLE STAINS, BARN AND ROOF PAINTS.

512. Shingle stains. The manufacture of really high-

grade shingle stains has been accomplished by only a

very few paint firms, as the basis of success is the ob-

taining of the right kind of creosote oil. There are a

number of creosote oils on the market which have been

freed from naphthalene sufficiently so that the naph-thalene will not separate out when chilled or when the

prepared stain is subjected to cold weather; but it will

be observed that such creosote oils will be low in the

phenyloid or preservative bodies, and therefore will ex-

ert little preservative action toward the wood, or else

the prepared stain changes color in the package. This

is particularly noticeable with the greens; the changewill begin within a few weeks after being prepared and

continue until the color has gone over to a dirty brown.

A close examination will show that this change is usu-

ally not due to the alteration of the chrome green, but

to the precipitation of a tarlike substance which forms

a coating over the chrome-green particles and destroys

their tinting strength.

513. Examination. It is necessary, if a high-strength

creosote oil is to be used, to refine it, which has been

found to be financially profitable to only a few manu-

facturers, and who use all of their product in the

preparation of their own goods. The paint chemist,

therefore, should not accept a creosote oil from the dis-

tillation figures only, but should conduct a practical try-236

SHINGLE STAINS, BARN AND ROOF PAINTS. 237

out, noting any changes that may take place in a can

of the prepared stain, for two to three months. Theauthor has made numerous analyses of the leading

brands on the market, but found very little similarity

in the products examined. Some were simply cheaplinseed-oil paints and much reduced with naphtha, con-

taining no creosote oil at all, the majority contained

varying amounts of a weak creosote oil, low in phenyl-oid bodies, possessing little preservative action.

514. The following analysis reduced to formula is

representative of a medium-priced, fairly high-grade

shingle stain:

Creosote oil 10 gal.Solvent naphtha

l 12 gal.Paraffine oil . j; . ;. 12 gal.Linseed oil ..... .

v

2 gal.Asbestine pulp 9 Ibs.

Chrome green, C. P 15 Ibs.

1 A commercial mixture of benzole, toluene, and xylene.

515. Barn paints, roof paints, fence paints, etc. The

prices at which these paints are offered for sale precludethe use of high-grade materials such as should be used

in first-quality house paints. They are, however, usu-

ally satisfactory for the purpose intended. The samemethods of analysis as are applied to house paints are

applicable to barn and roof paints. The latter, how-

ever, usually offer numerous complexities, and the ana-

lytical results obtained must be interpreted with care

and discrimination. It is by no means uncommon for

manufacturers who label their goods as to compositionto include, under the term Japan drier, a large percent-

age of naphtha or of kerosene oil, and under the term

varnish, various rosin, rosin-oil, cottonseed-oil, soya-

bean-oil, and corn-oil preparations. The detection of

these various oils is comparatively easy, but the deter-


mination of the amounts present, especially of the last

four, is largely a question of judgment rather than of

exactness.

516. Analyses. The following analyses made by the

author are believed to be representative of the combina-

tions on the market:

CHAPTER XXIX.

ANALYSIS OF JAPANS AND DRIERS.

517. At the present time the terms "Japan" and

11drier" are interchangeable and refer to the same

line of products, manganese linoleate, lead linoleate,

resinate of manganese, resinate of lead, or mixtures of

these compounds. Originally Japan contained a con-

siderable quantity of dissolved resin, constituting a

preparation that on drying gave a film of considerable

hardness and lustre, but this distinction has largely

disappeared. These compounds should not be con-

fused with baking Japans, which represent an en-

tirely different class of products and which will not be

discussed at this time. Japans and driers are usuallymade by heating the oxides of lead and manganese or

borate of manganese with linseed oil or the various

resins, and dissolving the melted mass in turpentine,benzine or mixtures of both.

518. Determination of the drying salts. The salts

generally used are

Litharge, PbORed lead, Pb 3O 4

Oxide of manganese, Mn02

Borate of manganese, MnB2O 4

occasionally Zinc sulphate, ZnSO4

and Zinc oxide, ZnO.

Weigh 25 grams of the drier into a 250 c.c. Erlen-

meyer flask and dilute with 25 c.c. of a mixture of equal

parts of benzine and turpentine. Add 50 c.c. of dilute

239


hydrochloric acid (1.10 sp. gr.). Allow to stand 1

hour, shaking thoroughly at intervals of 10 minutes.

Immerse the flask in a beaker of hot water, at a con-

siderable distance from the flame. When the contents

of the flask are hot, shake with a circular motion, avoid-

ing undue pressure in the flask. Allow to stand until

cool, so as to be sure that the drier has been whollydissolved. Pour into a separatory funnel, draw off

the aqueous layer into a casserole, wash the oil portion

twice with warm water, adding the washings to the

casserole and evaporate to dryness under the hood.

Dissolve in dilute nitric acid with the aid of heat, filter

into a 250 c.c. graduated flask and after washing thor-

oughly make up to the mark.

519. Lead. To an aliquot portion add 5 c.c. of dilute

sulphuric acid and evaporate on the hot plate until

white fumes of sulphur trioxide appear. Cool, add

cautiously 50 c.c. of water, heat to boiling, cool slightly,

and add 50 c.c. of alcohol. Allow to stand one-half

hour, filter onto a Gooch crucible, wash with 50 per

cent alcohol, dry, heat gently and weigh as lead sul-

phate.

520. Manganese. To an aliquot portion of the sam-

ple add 5 c.c. of sulphuric acid, dilute with 10 c.c. of

water, and evaporate on the hot plate until all of the

hydrochloric acid is expelled as shown by copious evo-

lution of sulphur trioxide fumes. Cool, dissolve in

about 25 c.c. of water and heat carefully with occa-

sional shaking until all of the anhydrous sulphate of

iron has dissolved. Transfer to a 250 c.c. graduatedflask and add an excess of zinc oxide emulsion, obtained

by mixing C. P. zinc oxide with water. Avoid a large

excess, but sufficient to precipitate all the iron, so that

on standing the solution begins to settle clear and some

ANALYSIS OF JAPANS AND DRIERS. 241

zinc oxide can be seen in the bottom of the flask.

Cool and make up to the mark. Transfer an aliquot

portion to a beaker or flask and add an excess of a sat-

urated solution of bromine water, and about 3 gramsof sodium acetate. One c.c. of a saturated solution of

bromine water will precipitate about 0.01 gram of

manganese. Boil about 2 minutes. Filter and wash

with hot water. The filtrate must be perfectly clear.

Place the filter containing the washed precipitate back

in the beaker or flask in which the precipitation was

made. All traces of bromine must be entirely ex-

pelled.

Add an excess of standard oxalic acid solution and

about 50 c.c. of dilute sulphuric acid (1:9) and heat

nearly to boiling with gentle agitation until the pre-

cipitate is entirely dissolved. Dilute to about 200 c.c.

with hot water and titrate with standard perman-

ganate.

521. Zinc. Zinc sulphate and zinc oxide are but

little used at present in driers. If present zinc may be

estimated in the filtrate from the lead sulphate, as de-

scribed under the analysis of mixed paints containingumbers and siennas.

522. Calculations. The color of the drier gives a clue

as to the combinations used, borate of manganese beingused in light colored driers, oxide of manganese in dark

driers," and the oxides of lead in medium colored driers.

By far the most common combination is a mixture of

borate of manganese and litharge.

523. Determination of the volatile oils. Five grams of

the drier are quickly weighed into a flat-bottomed dish

(a petri-plate is the most suitable), dried for 3 hours at

150 C., cooled and weighed. Loss in weight repre-

sents very closely the amount of volatile thinner pres-


ent, and in the samples analyzed by the author the

volatile thinners constituted 63 to 68 per cent byweight.

524. Separation of benzine and turpentine. About 100

grams of the drier are distilled to the point of incipient

decomposition, the distillate redistilled and the benzine

estimated by the Sulphuric Acid Number, as described

under the analysis of volatile oils.

525. Detection of rosin. About 1 c.c. of the drier is

dissolved in 15 c.c. of acetic anhydride, warming until

the solution is complete. Cool, filter, place a few

drops of the filtrate on a crucible cover and add a dropof sulphuric acid, so that it will mix slowly. If rosin

is present a characteristic fugitive violet color results.

Linoleate driers sometimes give a color resembling that

of rosin driers, and it is better to evaporate a portion of

the drier to a syrup consistency, treat with alcohol, and

test the alcoholic extract.

526. Practical tests. The chemical analysis of a Japanwill give very little information regarding its efficiency,

since the latter is largely dependent upon the condi-

tions of manufacture. The following specifications,1 as

adopted and used by the Philadelphia and Reading

Railroad, give very excellent methods for determiningthe efficiency of a Japan."The material desired consists of a pure turpentine

hardener and oil drier, conforming to the following:

1st. When equal parts by weight of the Japan and

of pure turpentine are thoroughly mixed and pouredover a slab of glass, which is then placed nearly vertical

at a temperature of 100 Fahrenheit, with a free access

of air, but not exposed to draught, the coating shall be

1 Practical Testing and Valuation of Japan, by Robert Job, Chem-ical Engineer, Vol. IV., No. 5.

ANALYSIS OF JAPANS AND DRIERS. 243

hard and dry, neither brittle nor sticky, in not exceed-

ing 12 minutes.

2d. When thoroughly mixed with pure raw linseed

oil at the ordinary temperature in proportions of 5

per cent by weight of Japan to 95 per cent by weightof raw linseed oil, no curdling shall result, nor anymarked separation or settling on standing.

3d. When the above mixture is flowed over a slab

of glass, which is then placed nearly vertical, at a

temperature of 100 Fahrenheit, with free access to

air, but not exposed to draught, the coating shall dry

throughout, neither brittle nor sticky, in not exceeding2 hours.

4th. When five cubic centimeters of the Japan are

poured into 95 cubic centimeters of pure turpentine at

the ordinary temperature, and thoroughly shaken, a

clear solution shall result, without residue, on standing1 hour.

5th. After evaporation of the turpentine, the solid

residue must be hard and tough, and must not 'dust'

when scratched with a knife.

6th. Benzine or mineral oil of any kind will not be

permitted.

Shipments which are not closely in accordance with

these specifications, or which are not of uniform quality

throughout, will be returned at the expense of the

shipper/'

527. The temperature of 100 F. is obtained by the

use of a suitable oven. The strips of glass used being4 inches long by 2 inches wide. They are so placed in

the oven that there is free access of air, but no draught.The bulb of the thermometer is placed beside the glass

strips and the dryness of the film tested opposite the

bulb of the thermometer.


The addition of rosin renders the dry film brittle and

hence will "dust" when scratched with a knife.

The majority of driers used for house and barn paints

are weak driers, and will not meet the above require-

ments. However, if the chemist will test out a few

high-class driers by the above specifications, he will

have but little trouble in estimating the value of the

cheaper and inferior driers.

The United States Treasury specifications for man-

ganese borate require that it be free from by-products,

and that, other properties being satisfactory, prefer-

ence will be given to the article containing the least

amount of alkali.

Another practical test much in vogue among practi-

cal painters and shop foremen is to make a semi-paste

with moisture-free litharge and the drier. High-class

driers will remain three to four days before showing a

decided tendency to thicken or harden; cheap rosin

driers will begin to harden in a comparatively short

time.

CHAPTER XXX.

ANALYSIS OF SHELLAC AND SPIRIT VARNISHES.

Analysis of Shellac.

528. The most common adulterant of shellac is com-

mon rosin or colophony. Sabin, in his Technology of

Paint and Varnish, says that, "It is reported and prob-

ably true, that large quantities of common rosin are

shipped to India and used as an adulterant of gumshellac."

529. Detection of rosin. About 1 gram of the sampleis dissolved in about 15 c.c. of acetic anhydride, warm-

ing gently until the solution is complete. Cool thor-

oughly under the tap. The rosin will remain in solution

while the greater part of the shellac will separate out.

Filter. Place a few drops of the filtrate on a porce-

lain crucible, cover, and add by means of stirring rod

one drop of sulphuric acid (34.7 c.c. sulphuric acid and

35.7 c.c. water) so that it will mix slowly. If rosin is

present a characteristic violet fugitive color results. Apure shellac should give no coloration.

530. Estimation of rosin. The amount of rosin pres-

ent is best estimated by means of the iodine number.

For this purpose the Hanus method is to be preferred to

the Hubl or Wijs method. The Hubl for a long time

has been the official method, but it has several faults

which affect its accuracy. It rapidly loses strength

and is so slow in its reaction with some oils, such as

linseed oil, that a serious error is brought about by245


the change in strength of the solution during the reac-

tion. Another objection to the Hubl method is that

practically each chemist uses a modification of his

own as regards the time necessary for the solution to

remain in contact with the substance to be tested.

In their workings the Hanus and Wijs methods are

very similar, but the Hanus solution is much easier to

prepare and the results obtained more nearly corre-

spond to those obtained by the Hubl method. As

most of the published data relating to the iodine num-bers of oils, fats, etc., has been obtained by the use of

the Hubl method, this fact is of considerable impor-tance in making comparisons.

531. The Hanus solution is prepared and used as

previously described.

0.2 gram to 0.3 gram of the ground sample is intro-

duced into a 250 c.c. Erlenmeyer flask; 20 c.c. of

glacial acetic acid added, and the mixture warmeduntil the solution is complete, except for the wax.

10 c.c. of chloroform is added, the solution cooled to

room temperature, and 25 c.c. of Hanus solution added,

the flask stoppered, allowed to remain in the dark or

in diffused light for 1 hour, with occasional shaking.

10 c.c. of potassium iodide solution and 100 c.c. of

water are added and titrated with tenth-normal thiosul-

phate, using starch as an indicator in the usual man-ner. Blank determinations should be made each time.

EXAMPLE:

Wt. of sample = 0.4 gram.A blank of 25 c.c of Hanus solution required 55 c.c.

of thiosulphate.

1 c.c. of thiosulphate = .0125 gram of iodine.

Titration of unabsorbed iodine = 49.5 c.c. thiosulpkate.

ANALYSIS OF SHELLAC AND SPIRIT VARNISHES. 247

55.0 49.5 = 5.5 c.c. of thiosulphate equivalent to

iodine absorbed.

(5.5 X 100 X .0125) ^ 0.4 = 17.2 per cent iodine

absorbed.

532. Iodine Numbers of shellacs obtained from the

leading wholesalers and jobbers of the United States,

supposed to be strictly pure:1

Analysis of Shellac Varnish.

533. Composition. A varnish having the proper con-

sistency is prepared by dissolving 45 parts of shellac in

55 parts of grain alcohol of 94 per cent strength or

about 5 pounds of shellac per gallon of alcohol. In

place of the expensive grain alcohol, some manufac-

turers substitute wood alcohol or Columbian spirits,

which is rectified wood aJcohol. The poisonous prop-erties of wood alcohol are well known, and on account

of its injurious effects great care should be exercised

in the use of varnishes containing it. Shellac varnish

1Analyses by author.

2 Libermann-Storch Reaction.


is often adulterated with rosin, thus producing a prod-uct of an inferior quality. The sophistication of

varnish with this substance is well described by Lang-muir: 1

"Starting out with an adulterated shellac, the

varnish maker, secure in his belief that rosin cannot be

detected in the solution, proceeds to add still morerosin. What has been said in regard to adulteration

of shellac fades into insignificance in comparison with

that practice in the manufacture of shellac varnishes.

Shellac varnishes are sold containing no shellac. 'Pure'

shellac varnishes, grain alcohol, may be purchased at

less cost than the alcohol."

534. Determination of the body of shellac varnishes.

3 to 5 grams of the well stirred sample is weighedinto a weighed flat-bottom petri-dish and evaporatedto a constant weight in the steam oven. The result is

calculated in pounds per gallon. If a platinum evap-

orating dish be used and the evaporation conducted

over a water bath, the amount taken should not be

over 1 gram. Taking the weight of a gallon of woodalcohol at 60 F. as 6.75 pounds, the pounds per gallon

may be ascertained by means of the following table: 2

Per cent. PoundsResidue. per Gallon.

30.77 3.0

34.15 3.5

37.20 4.0

40.00 4.5

42.55 5.0

44.90 5.5

47.06 6.0

49.05 6.5

50.91 . . 7.0

52.63 7.5

54.23 8.0

1 Determination of Rosin in Shellac, J. Soc. Chem. Ind., January 1,

1905.2 Ibid.


535. Determination of the strength of the alcohol used.

The strength of the alcohol may be calculated, know-

ing the per cent of residue as determined above and

the specific gravity of the varnish. The calculation is

best illustrated by the following example:

5 grams of varnish yielded a residue of 2.300 grams.

The specific gravity of the varnish was 0.9445 at

15.5 C.

100 grams of the varnish gave 2.300 X 20 = 46.00

grams of residue or 46.00 per cent.

The alcohol by difference 100.00 - 46.00 = 54.00

grams or 54.00 per cent.

Average specific gravity of shellac itself = 1.145.

The volume taken up by the shellac in the varnish

would be 46.00 -*- 1.145 = 40.17 c.c. in 100 grams of

varnish.

The specific gravity of the varnish was 0.9445.

100 c.c. would weigh 94.45 grams and hence 100

grams would occupy 105.9 c.c.

105.9 c.c. 40.17 c.c. = 65.73 c.c., the volume occu-

pied by 54.00 grams of alcohol solvent.

54.00 -s- 65.73 = 0.8215, the specific gravity of the

alcohol. From the alcohol tables this will be found to

correspond to 90.5 per cent of grain alcohol. If de-

sired a portion of the varnish may be distilled until

the decomposition point is reached and the strength of

the alcohol determined from the specific gravity of the

distillate.

536. Examination of the solvent. One hundred gramsof the varnish are carefully distilled to the point of in-

cipient decomposition. If necessary the distillate maybe redistilled.

537. Detection of benzine. Dilute a portion of the


distillate with three or four volumes of water. If

benzine is present it will separate but.

538. Columbian spirit and wood alcohol. The test for

acetone, which is always to be found in wood alcohol,

will distinguish between Columbian spirit and woodalcohol.

539. Detection and estimation of wood alcohol in mix-

tures with grain alcohol. Qualitatively, the methylalcohol may be detected by the following method:

Dilute a portion of the distillate until the liquid con-

tains approximately 12 per cent of alcohol by weight.

Oxidize 10 c.c. of the liquid in a test tube as follows:

Wind copper wire 1 mm. thick upon a rod or pencil 7 to

8 mm. thick in such a manner as to enclose the fixed

end of the wire and to form a close coil 3 to 3.5 cm.

long. Twist the two ends of the wire into a stem 20

cm. long and bend the stem at right angles about 6 cm.

from the free end, or so that the coil may be plungedto the bottom of a test tube, preferably about 16 mm.wide and 16 mm. long. Heat the coil in the upper or

oxidizing flame of a Bunsen burner to a red heat

throughout. Plunge the heated coil to the bottom of

the test tube containing the diluted alcohol. With-

draw the coil after a second's time and dip it in water.

Repeat the operation from three to five times, or until

the film of copper oxide ceases to be reduced. Cool the

liquid in the test tube meanwhile by immersion in water.

540. Add 1 c.c. of strong ammonia to the oxidized

liquid in a casserole and expel the acetaldehyde by

boiling gently over a direct flame until the vaporceases to smell of ammonia. Add 2 to 3 drops of

strong hydrochloric acid to set free the formaldehydewhich has been retained as hexamethyltetramin, and

bring the liquid momentarily to a boil; cool promptly


by immersion of the casserole in water and test for

formaldehyde by the modified resorcin test, as fol-

lows:

Add to the liquid remaining 1 drop of a solution

containing 1 part of resorcin in 200 parts of water, and

pour the mixture cautiously into a test tube contain-

ing 3 c.c. of concentrated sulphuric acid, holding the

tube in an inclined position in such a manner that the

two liquids shall not mix. Allow it to stand 3 min-

utes, then sway the tube slowly from side to side in

such a manner as to produce a gentle rotary motion

of the two layers. Persist in this operation, if neces-

sary, for a minute or more, using a piece of white

paper for a background, and producing only a very

gradual and partial mixing of the acid and water.

Nearly half of the acid should remain as a distinct

unmixed layer at the end. When methyl alcohol is

present, the shaking causes the separation of more or

less voluminous flocks of a very characteristic rose-red

color. The appearance of colored zones or flocks of

other hues, even when tinged with red, or of a rose-red

solution without flocks, should never be considered

proof of the presence of methyl alcohol. However,if the flocks are reddish brown, or if the upper layer

has a pronounced red, it is often well to repeat the

test.

By this method for the removal of acetaldehyde 10

per cent of methyl alcohol may be readily detected,

and an experienced operator may detect with certainty

a less amount.

541. Quantitatively the methyl alcohol may be esti-

mated by the method of Thorp and Homes.

This method depends upon the fact that in the pres-

ence of potassium dichromate and sulphuric acid in a


closed vessel at 100, ethyl alcohol is converted into

its theoretical equivalent of acetic acid, while with

methyl alcohol, the product resulting from the oxida-

tion is always carbon dioxide and water. It has, how-

ever, been found that for each gram of ethy] alcohol

present in the solution 0.01 gram of carbon dioxide

may be formed and this correction should be made in

all determinations.

The specific gravity is determined by means of a

pycnometer. The total per cent of the alcohol is prac-

tically the same as the per cent of ethyl alcohol of

the same specific gravity.

542. The methyl alcohol is determined by convertingit into carbon dioxide by means of sulphuric acid and

potassium dichromate in the Knorrs' apparatus de-

scribed under the estimation of carbon dioxide in

white lead.

Weigh into the flask 20 grams of potassium dichro-

mate, connect the apparatus after having weighed the

soda-lime tubes. Introduce through the stop-cock

funnel an exact volume of the alcohols not to exceed

4 grams of the mixed alcohols, and an amount of water

equal to 50 c.c. less the number of c.c. of alcoholic

solution, 80 c.c. of sulphuric acid (made by diluting

one volume of concentrated acid with four volumes of

water) are added, well shaken and allowed to stand

18 hours. Dissolve 10 grams of potassium dichromate

in 50 c.c. of water, add through the funnel, then add

50 c.c. of concentrated sulphuric acid and heat the

contents of the flask to boiling for about ten minutes,

the carbon dioxide being carried off by a current of

air through the apparatus. The heat is now removed

and the current of air continued for a few minutes

longer. Disconnect and weigh the soda-lime tubes.

ANALYSIS OF SHELLAC AND SPIRIT VARNISHES. 25.3

Calculate the methyl alcohol from the proportion

1.373 : 1 : : wt. CO2 obtained : x

x = wt. methyl alcohol,

the theoretical oxidation of 1 gram methyl alcohol

producing 1.373 grams of carbon dioxide.

EXAMPLE.

Specific gravity of sample, 0.7992

Weight of sample used, 1.0118 grams

Weight of carbon dioxide, 1.3810 grams1.373 : 1 : : 1.3810 : x

x = 1.006 grams methyl alcohol.

1.0118 : 1.1006 : : 100 : y

y = 99.4 per cent methyl alcohol.

543. If ethyl alcohol is present, the correction pre-

viously referred to, of 0.01 gram carbon dioxide for

each gram of ethyl alcohol, should always be applied.

The weight of the methyl alcohol subtracted from the

weight of the mixed alcohols (calculated from the sp.

gr.) gives the weight of the ethyl alcohol, approxi-

mately. The weight obtained by 0.01 gives correction

to be deducted from the total carbon dioxide, for the

recalculation of the weight of methyl alcohol. It is

obvious that a very slight error is thus introduced,

but the writer believes that it is so small that it maybe safely neglected.

544. Detection and estimation of rosin. The residue

remaining after the drying of the varnish in the deter-

mination of the "body" may be used for the detection

of rosin as described under the examination of shellac.

If much rosin is present, it is not safe to take the

residue after evaporation for the quantitative estima-

tion as has been shown by Langmuir. "A little rosin


(iodine value 224.3) was dissolved in alcohol, evapo-rated on the water bath and heated 5 hours. It then

showed a value of 148.2. Similarly, a dark rosin 175.7

fell to 131."

A quantity of the varnish sufficient to yield 0.2 to 0.4

gram of residue is weighed from a small vial, providedwith a perforated stopper carrying a shortened 1 c.c.

pipette, into a 200 c.c. Erlenmeyer flask; the weight of

the sample used being thus obtained by difference.

The sample in the flask is carefully evaporated at a

low temperature until pasty and then dissolved in the

requisite amount of acetic acid and chloroform and

the iodine number then determined in the usual man-ner. The error due to the action of the small amountof alcohol remaining in the pasty mass on the thio-

sulphate is negligible.

In calculating the per cent of rosin the iodine values

of 150 1 for rosin, 16 1 for unbleached and 11 1 for

bleached shellac may be used. If other resins are

present, as sandarac, etc., these can only be calculated

in the terms of rosin.

545. Estimation of rosin, Mannhardt's method. 2 Five

grams of gum shellac or 10 grams of shellac varnish are

weighed into a casserole flask, and the solvent ex-

pelled on the water bath. The residue is saponified

with alcoholic potash, the alcohol expelled, and the

residue taken up in 100 c.c. of hot water. At this

point any wax present may be extracted with benzine

(sp. gr. 730), the benzine evaporated off, and the resi-

due weighed.The solution of the soaps is treated with 50 c.c. ben-

zine (sp. gr. .730), shaken vigorously, and, before the

1 Average values obtained by author.2 Hans Mannhardt, Chemist, Heath & Milligan Mfg. Co.


emulsion has time to separate out, add dilute sulphuric

acid in slight excess. The shellac acids immediately

coagulate, and all rosin acids go into the benzine,

which is readily separated, filtered and evaporated in

a weighed beaker. The shellac acids are absolutely

insoluble in benzine. Damar and possibly sandarac

will behave like rosin.

546. Practical test for brewers* varnish. Varnishes for

brewers'

purposes should be made from pure shellac

and grain alcohol 94 per cent strength. They may be

tested out by varnishing a strip of wood 6 inches long

by 3 inches wide, and a quarter of an inch in thickness,

and after drying immerse half of the strip in 4 per cent

alcohol for 48 hours. A varnish made from impureshellac or alcohol of less than the proper strength will

soon turn white.

547- ANALYSES OF SHELLAC VARNISHES. 1

1 Analyses by author.

2 Liebermann-Storch reaction produces a somewhat different color than that usually

given by rosin, hence these samples may be adulterated with other gums.

548. Damar varnish. The following specifications

adopted by the Navy Department, May, 1904, will


serve for the practical testing and valuation of damarvarnish.

Damar varnish must be made from the very best

quality of damar gum in a solution containing at least

50 per cent of gum and 45 per cent of turpentine, the

gum to be digested cold and well settled. The varnish

must be as clear as and not darker than the standard

sample, and must be free from benzine, rosin, lime, or

other mineral matter. Its specific gravity at 60 F.

must be about 0.950, and its flash point between 105

and 115F. It must set to touch in not more than

20 minutes, and when mixed with pure zinc oxide

must show a smooth, glossy surface equal to that

shown by the standard sample.

549. Tests. Besides chemical tests to determine the

above qualities, and practical tests to determine its

qualities of finish, a board properly coated with a mix-

ture of zinc and the liquid will be exposed to the

weather for a period of 1 month, and at the end of

this time must have stood exposure equally as well as

the standard sample. A similarly prepared samplewill also be baked at 250 F., and must not at this

temperature show any greater signs of cracking, blis-

tering, or any other defects than standard samples

under the same conditions. Another sample, simi-

larly prepared, will be exposed in a dark room at ordi-

nary temperature for a period of 1 month and at the

end of this time must not have turned darker to any

appreciable degree than the standard sample.

CHAPTER XXXI.

ANALYSIS OF OIL VARNISHES.

550. Analysis of oil varnishes. As stated by Hurst,

"The analysis of oil varnishes is one of great difficulty,

as it is quite impossible to separate all the ingredients

from one another." However in spite of the unsatisfac-

tory state of our present knowledge of varnish analysis,

a distillation and separation will give an approximate

idea of the quantity and kind of volatile solvents used.

Treating the residue by Twitchell's method, will give

approximately the amount of oil and the amount of

gum present in the varnish and an examination of the

physical and chemical properties of the separated gummay give an approximate idea of its hardness, and

throw some little light on its probable source. The

presence of lime, color produced by the Liebermann-

Storch reaction, acid figure and iodine absorption will

indicate the presence of rosin and to some extent the

amount present. With these tests, in conjunction with

the solubility of the separated gum, the original char-

acter of the varnish, e.g., the pouring of a portion of

the sample on a sheet of glass, noting how it flows,

dries, the kind of film produced, its resistance to abra-

sion, to moisture, its elasticity, etc., and a comparisonmade with varnishes of known composition and similar

properties, a very shrewd guess can be made as to howthe varnish under consideration must be duplicated, or

in other words, the approximate amounts of the dif-

ferent gums required to produce a similar product.257


551. On the other hand, a proximate analysis of a

varnish furnishes us with but a small amount of help-

ful information, as the gloss, working qualities, and

durability depend largely on the quality of gum used,

the quality and treatment of the oil, the quality of the

driers used, and especially as to how the varnish was

prepared, as regards heat, method of cooking, ageing,

filtering, etc. On these essential points a chemical

analysis tells us but little. That greater light will even-

tually be thrown on the problems involved, the author

has not the slightest doubt, but meanwhile interpre-

tations based solely on chemical analyses are liable to

be more or less misleading; but taken in connection

with physical tests, carefully made, the value of var-

nishes can be determined with considerable accuracy.

552. Specific gravity. The determination of the spe-

cific gravity is of considerable importance and should

be made with a pycnometer at 15.5 C.

553. Viscosity. The determination of the viscosity

of a varnish will throw considerable light on its work-

ing qualities. Any of the standard types of viscosim-

eters may be used for varnish work, but the Doolittle

Torsion Viscosimeter offers several advantages over

the others.

554. Separation, identification, and estimation of the

volatile oils. Seventy-five grams of a uniform sampleof the varnish is weighed into a 500 c.c. distilling flask,

provided with a tube leading very nearly to the bot-

tom, the other end of which is connected with a steam

supply. The flask is also provided with a thermom-

eter, the bulb of which dips below the surface of the

varnish, and the flask then connected with a rather

long condenser. By means of an oil bath the varnish

is heated to 130 C., and a current of steam passed

ANALYSIS OF OIL VARNISHES. 259

through, until about 500 c.c. of water has passed over,

or until the steam ceases to carry over any morevolatile oil. It is advisable to collect the distillate

directly in a separating funnel. When the volatile oil

has completely settled out, the water is drawn off and

the oil transferred to a weighed flask, weighed, and the

percentage calculated. The aqueous distillate will con-

tain a small quantity of the volatile oil equal to about

0.4 gram per hundred c.c. This correction should be

made in calculating the percentage.

liThe constituents of the volatile oil and the amount

of^petroleum products present may be determined in

th<5 same manner as in mixed paints."

555. Separation of the resin gums from the oil, Twitch-

elPs method. The flask containing the residue of oil

and gum is connected with a return condenser, 150 c.c. of

normal alcoholic potash added, the flask heated care-

fully on a water bath to avoid bumping and finally

heated over a free flame for about an hour. Thesolution is then cooled and separated from the residue,

which is again treated with alcoholic potash, and the

process continued until as complete a saponification

as possible has been made; usually a small residue of

about 1 per cent remains. The different alcoholic so-

lutions are united, neutralized with hydrochloric acid,

the excess of alcohol evaporated off, and the fatty

acids and gums removed with successive portions of

ether. The ethereal solution is distilled to remove

the ether, a small quantity of absolute alcohol added,

and the flask again heated gently, the alcohol carrying

off the last traces of water. About 10 volumes of

absolute alcohol are added to the dry gums and acids,

the solution being kept cold by ice and dry hydro-chloric acid gas is passed in until the solution is sat-


urated. This will usually take from 30 to 45 minutes.

The flask and contents are allowed to stand for about

an hour, then diluted with about 5 volumes of hot

water, and boiled until clear; the heating being con-

ducted gently to avoid frothing.

556. The contents of the flask are mixed with a little

petroleum ether, boiling below 80 C., and transferred

to a separating funnel, the flask being washed out with

the same solvent. The petroleum ether layer should

measure about 50 c.c. After shaking, the acid solu-

tion is run off and the petroleum ether layer washed

once with water, and then treated in the funnel with

a solution of 2.5 grams of potassium hydroxide and

20 c.c. of alcohol in 200 c.c. of water. The ethylic

esters dissolved in the petroleum ether will then be

found to float on top, the rosin acids having been

extracted by the dilute alkaline solution to form rosin

soap. The soap solution is then run off, decomposedwith hydrochloric acid, and the separated rosin acids

collected as such, or preferably dissolved in ether, and

the whole evaporated in a small weighed beaker on

the water bath. A small quantity of absolute alcohol

is added, and the evaporation repeated. Finally, cool

in the desiccator and weigh. This will give approxi-

mately the amount of gums present in the varnish.

Any residue insoluble in the 10 volumes of absolute

alcohol above mentioned is weighed up and its weightadded to the weight of resin gum.

557. Separation of the gums from the oil, Scott's

Method. 1 In separating the gum, by this method, it is

necessary to know whether the sample is a Long Oil or

Short Oil Varnish, i.e., whether it contains a large or

small amount of linseed oil. Hard oil finishes, inte-

1Drugs, oils, and paints, XV., No. 4, page 132, and No. 6, page 219.


rior varnishes, and rubbing varnishes are usually short

oil varnishes, while carriage and similar varnishes are

long oil varnishes.

In order to determine to which class a varnish be-

longs, about 10 c.c. of the sample is poured into a

beaker and 50 c.c. of benzine, previously cooled to

about 5 C., added. If the sample be short oil varnish

the gums will be partially precipitated, while a long

oil varnish will show but little change. The color of

the precipitated gum may be considered as another

indication, a light colored precipitate denoting a short

oil, and a dark colored precipitate, a long oil varnish.

558. Short oil varnishes. A beaker of about 150 c.c.

capacity, provided with a stirring rod, is carefully

weighed, and about 10 grams of varnish weighed into

it. Cool to below 10 C. Fifty c.c. of petroleum ether

that has previously been cooled to below 3 C. is pouredinto the beaker and the contents stirred. The beaker

is placed in a freezing mixture for about an hour, or

until the precipitated gums have settled. ^L, we^559. Place a filter paper that has been dried^in the

oven, in the suction funnel. Moisten and suck the

filter free from surplus moisture, pour in the gasoline,

retaining as much of the resins as possible in the

beaker. Add another 50 c.c. of ice cold petroleum

ether, and allow to stand as before on the freezing

mixture. Meanwhile pour 25 c.c. of ice cold water

on the filter paper, allowing it to run into the petro-

leum ether filtrate, which is then vigorously shaken upso as to thoroughly mix the water and petroleum

ether, which causes the gum held in solution by the

ether to precipitate, and on refiltering is retained.

The second ether solution that has been cooling is now

poured on to the filter along with the precipitate, rins-

262 PAINT AND'VARNISH PRODUCTS.

ing out the beaker with ice cold petroleum ether.

Treat with 25 c.c. of ice cold water, shaking and refilter-

ing, as described above. Repeat this operation twice,

transfer the filter, and precipitate to the weighed

beaker, and dry in the hot air oven at 105 to 115 C.

and weigh. Increase in weight, over that of the beaker,

stirring rod and filter, represents the weight of the

gum.The petroleum ether solution containing the varnish

oils is poured into a weighed beaker, the excess of pe-

troleum ether evaporated off with due precautions,

and the beaker placed in the hot air oven for 3 hours

at 150 C., cooled and weighed. The residue repre-

sents the fixed oils in the varnish.

560. Long oil varnishes. Distil off the thinners from

a portion of the sample. Weigh out 10 grams of the

gum and oil into a weighed beaker as described above,

cool down below 15 C. and add 50 c.c. of petroleumether cooled below C. Set in the freezing mixture

for an hour and finish exactly as described under short

oil varnishes. The separation of the total gum in

long oil varnishes is quite difficult and requires con-

siderable patience and experience. According to the

experience of the author, Scott's method gives some-

what low results, especially as rosin is quite soluble in

cold petroleum ether.

561. Determination of the so-called insoluble and

soluble gums. This method is somewhat similar to the

above, and, in the hands of a careful chemist, when run

alongside of standard varnishes, will throw consider-

able light on the nature of the sample in question.

Weigh 2 grams of the sample into a weighed 6-oz.

wide-mouth flask, add 2 c.c. of chloroform, 100 c.c. of

80 petroleum ether, gradually and with constant shak-


ing so as to avoid any precipitation, until 15 c.c. are

added, allow to stand over night. The precipitated

gums adhere to the bottom of the flask. Decant and

wash with a little petroleum ether. Dry to constant

weight as insoluble gum.The petroleum ether extract should be decanted

into a weighed beaker, the petroleum ether evapo-rated off and the beaker dried at 100 for seven to

eight days to constant weight. All linseed oil should

now be in the form of linoxyn. Digest over night

with chloroform, which will dissolve the gum, and

leave the linoxyn undissolved. Filter through cotton

wool. Evaporate off the chloroform, dry to constant

weight in the steam oven and weigh as soluble gum.A varnish to meet with the requirements of the

United States Treasury Department, among other

things, should contain not less than 25 per cent of

best quality imported gums, and must not contain

rosin or petroleum products.

Varnishes containing wood oil are liable to give mis-

leading results by the above method, as the whole or a

considerable portion of the wood oil will be precipitated

by the petroleum ether, depending on the length of

time and temperature to which the oil has been heated.

562. Detection and estimation of rosin in varnishes.

Qualitatively rosin may be detected as follows: Pour

about 5 c.c. of the varnish into a small separatory

funnel, add about 5 c.c. of carbon bisulphide, shake

and add 10 c.c. of acetic anhydride. Allow to stand

until complete separation takes place. Draw off the

lower layer, which is the acetic anhydride. Pour 1 or

2 c.c. of the acetic anhydride portion into an inverted

crucible cover, add carefully, by means of a stirring

rod, one drop of sulphuric acid (34.7 c.c. of sulphuric


acid to 35.7 c.c. of water) to the edge of the cover, so

that it will mix slowly with the acetic anhydride, if

rosin is present a characteristic fugitive violet color

will result.

563. The quantitative estimation of rosin in the

presence of other varnish gums is a problem of especial

difficulty. Gill,1

suggests a method based on compara-tive ester values. The ester value being obtained bysubtracting the free acid value from the saponification

value. The gums are separated from the oils byTwitchell's method, the last traces of moisture beingremoved by drying over sulphuric acid. Gill obtains

the following values for rosin and kauri.

By the use of the usual formula

100 (7-

n)

m nx

the percentage of adulteration may be approximated,as described in the chapter on the Analysis of the

Vehicle, in discussing cotton-seed oil.

564. Gill's method is open to considerable criticism,

as he directs that the Free Acid Value be obtained bydirect titration, and the Saponification Value by sapon-

ifying in practically an open flask. Dietrich 2 has

shown that direct titration gives acid values far too

low for all resin, because the complete neutralization

1 J. Amer. Chem. Soc., XXVIII., No. 12, page 1723.2Analyse der Harze, Balsane, und Gumminharze.

ANALYSIS OP OIL VARNISHES. 265

of the rosin acid proceeds slowly. As an illustration

of this point, Worstall 1

gives the following experiment.11Several portions of a sample of kauri, whose acid

number has been accurately determined as 103, were

weighed out and the acid number determined by in-

direct titration at different intervals of time. Theresults were as follows:

Time. Acid No.

5 minutes 82

1 hour 92

3 hours 96

6 hours 101

12 hours 102

18 hours 103

565. Regarding open saponification Worstall states

that "from the researches of Tschirch and his pupils, it

appears that the copals consist of 'resenes' neutral

compounds containing oxygen and possibly of an alde-

hyde nature and of the resin acids. Other investi-

gators have noted the fact that the copals will absorb

oxygen, and evidently the increase in acid numberand decrease in iodine absorption is due to the oxida-

tion of these 'resenes/ by contact with the air, to resin

acids. . . . That this increase in the acid number is

actually due to oxidation, the following experimentswill illustrate:

'

"A number of samples of Kauri were selected, each

one finely powdered, and its acid and iodine numbersdetermined. These samples were then left four monthsin open bottles exposed to the air, and the powderedresins stirred from time to time to promote oxidation.

At the end of this time their constants were again de-

termined with the following results.

1 Chemical Constants of Fossil Resins, J. A. Chem. Soc., XXV., page860.


"Samples 1, 2, 3 and 4 were hard, 'bold' gum of

highest quality, while samples 5 and 6 were of a soft,

spongy, lowest grade Kauri, in which oxidation had

already made much progress before the experimentwas carried out.

"This oxidation proceeds rapidly in presence of alka-

lies, so that open saponification with alcoholic caustic

potash gives acid numbers that are much too high.

Doubtless this fact, in connection with the impossi-

bility of obtaining correct acid numbers by direct titra-

tion, has led to the reporting of ester values in resins

where no esters exist. That Kauri is free from esters

was shown by saponifying several samples in flasks

with return condensers, digesting for one hour on the

steam bath. In every case the saponification number

thus found was the same as the indirect acid number."

566. From the above data it is evident that, in order

to approximate the percentage of rosin in a varnish bythe so-called ester values according to Gill's method,each analyst must establish his own set of figures,

under certain definite working conditions, obtaining his

data from varnishes of known composition. Any vari-

ation of these conditions, either in time, factor or con-

dition of the gums, is certain to give different results.

Little that is reliable has been written concerning

the detection of the other varnish gums. Certain


resins, however, give some indication of their presence.

For instance, Kauri imparts a reddish stain to a var-

nish. Damar, if present in considerable quantity, can

be detected by its smell, especially in the dried var-

nish. It is seldom found in varnishes intended for

outside use.

567. In closing, a word should be said concerningwood oil. This product, the properties of which are

but little understood by the majority of chemists, is

finding a wide use among varnish manufacturers. It

is claimed by varnish manufacturers that by the use

of wood oil, varnishes containing a large amount of

rosin may be prepared, possessing satisfactory wear-

ing qualities and free from the objectionable features

of ordinary rosin varnishes. However, in light of the

rather heavy losses encountered by a number of var-

nish firms in endeavoring to prepare a satisfactory

rosin-wood oil varnish, the above claims of the varnish

manufacturers may be questioned somewhat. As to

the analysis of this type of varnish the author is not

aware of any suitable published method. It is said,

however, that it may be detected qualitatively bypractical varnishers, in quantities as low as five percent by the characteristic odor given off in sand-

papering a coat which has barely dried.

568. Navy specifications for interior varnish for naval

vessels, 1906. To be of the best quality and manu-facture and equal in all respects including body,

covering properties, gloss, finish and durability to

the standard samples in the general storekeeper's office,

navy yard, New York. To be made exclusively from

the best grade of hard varnish resins, pure linseed oil,

pure spirits of turpentine and lead manganese driers,

and to be free from all adulterants or other foreign


materials. The varnish must flash above 105 F., set

to touch in from 6 to 8 hours, and dry hard within 24

hours in a temperature of 70 F. It must stand rub-

bing with pumice stone and water within 36 hours

without sweating, and must polish in 72 hours with

rotten stone and water. To be as clear and not darker

than the standard sample, and to be equal to it in all

respects as above specified.

569. Navy specifications for black asphaltum varnish,

1906. Black asphaltum varnish must be of pure, high-

grade asphaltum of the very best quality, pure linseed

oil, pure spirits of turpentine and lead manganese

driers, and to be free from all adulterants or other

foreign materials, and must contain not less than 20

gallons of prepared linseed oil to 100 gallons of varnish.

It must not flash below 105 F. (open tester). It

must mix freely with raw linseed oil in all proportions ;

must be clear and free from sediment, resin, and

naphtha, when flowed on glass, and allowed to drain

in a vertical position; the film must be perfectly

smooth and of full body. It must set to touch in

from If to 2 hours, and dry hard in less than 20 hours

at 70 F. When dry and hard it must not rub up or

powder under friction by the finger. The applica-

tion of heat must quicken the time of drying and give

a harder film.

CHAPTER XXXII.

THE PRACTICAL TESTING OF VARNISHES.

570. The thorough practical testing of varnishes is an

exceedingly difficult matter for the average chemist, as

it requires long familiarity with the direct application

of varnishes under a large variety of circumstances and

conditions. However, there are several practical tests

which can be made without special difficulty, and

which will throw considerable light on the character of

the varnish, especially if the chemist be supplied with

a standard set of varnishes which he can run alongwith the sample to be tested, and have constantly byhim to enable him to check up his judgment by com-

parison.

571. Smell. The smell of a varnish will often tell

much concerning its value. A good, wholesome,

gummy odor usually indicates a varnish made from

good materials, while a strong, raw, pungent odor is

often, the sign of a cheaper grade of goods. Markedlyinferior articles can almost without exception be de-

tected in this manner. Occasionally the true odor of

the varnish is masked by a strong turpentine odor, in

which case allow a sample of the varnish to drain out

of a beaker for 3 to 5 minutes and then note the smell

of the portion adhering to the sides of the beaker, i.e.,

the "after smell," as it is called.

572. Consistency. The consistency of a varnish is

to a considerable degree regulated according to the

work for which it is to be used, and should be judged269


accordingly. There is a marked tendency, at the

present time, to make varnishes altogether too thin.

This may in part be due to the insistent demandsmade by contractors and other varnish users for goodsthat will "work fast" and dry quickly, but it should

be remembered that such varnishes do not afford the

measure of protection to the surface that is regarded

necessary by the best practical users of varnish.

573. Working and flowing. The working qualities

of the varnish under the brush will at once showwhether the chemist is dealing with a "long oil" or a

"short oil" varnish. A test board having been suit-

ably surfaced and filled either with thin shellac, or with

the varnish reduced with 25 per cent of turpentine,

dried and sandpapered down smooth, is given an even,

uniform coat of the varnish to be tested. The length

of time the varnish can be worked under the brush,

before it exerts a characteristic "pull" on the brush, is

indicative of the character of the varnish. If it per-

mits of sufficient time for thorough brushing out so

that a large panel could be coated and worked out

smooth, before it begins to pull on the brush, i.e.,

"set up," the sample would be considered a long oil

varnish, while if it begins to pull under the brush

almost at once, it would be considered a short oil

varnish. Naturally, there are varnishes which do not

exhibit these extremes, but usually the classification

can be made without difficulty.

574. Special notice should be taken of the way the

varnish flows out into a uniform surface, whether it

does so with ease, or slowly and with difficulty. In

applying the final coats the working and flowing can

be studied with greater exactness. Some varnishes

will work easily, others will work "tough," some

THE PRACTICAL TESTING OF VARNISHES. 271

"greasy/' etc.; with a little experience the chemist can

grade them with considerable accuracy. As men-tioned in a preceding paragraph, there are many var-

nishes on the market which are altogether too thin.

Such varnishes will work and flow with great ease

because of their excessive thinnessr and hence the con-

sistency must be taken into account when passing on

the working and flowing qualities.

575. Time of drying. The time a varnish requires

to dry properly, i.e., to harden thoroughly, is regulated

according to the purpose for which the varnish is to be

used. For instance, floor varnishes are supposed to

dry hard over night, while the average spar varnish

will require a much longer time. Hence the samplestested should be compared with the accepted standards

of those types of varnishes, both on the wood test sur-

face and on a sheet of glass, on which samples of the

varnishes have been placed and then set in. a dust-free

but unconfined place at an angle of about 30 degrees

from the perpendicular. The best results are secured

by resting the glass on a couple of small hooks, which

permits the varnish to drain freely. The rapidity of

the drying should be noted at regular intervals. Whendry, the tests should be saved for further examination.

576. The sponge test. After the requisite number of

coats have been applied to the test boards and the

finishing coat has hardened thoroughly, a sponge madeof several thicknesses of felt is thoroughly moistened

and laid on the varnished surface and allowed to re-

main for a stated number of hours undisturbed. Ahigh-grade varnish will either show no discoloration

at all, or will regain its color on drying, provided, of

course, that it has been suitably applied. A varnish

containing a large amount of rosin will be more or less


badly corroded, and will remain permanently white

and discolored. With a little practice by workingwith varnishes of known composition the chemist can

make a pretty shrewd guess as to the approximateamount of rosin present by the degree of discoloration.

Right here the author wishes to state that the use of

cheap inferior rosin varnishes has caused untold dam-

age. There is probably more rosin varnish sold than

all other grades put together. It is claimed by high-

class manufacturers that the addition of three or four

per cent of hardened rosin will enable the varnish

maker to melt his gums at a somewhat lower heat and

without darkening, thus making a better and lighter-

colored varnish; but the addition of rosin has passed

this point so far that a three or four per cent addition

is a very minor consideration indeed.

577. Another modification of the above test is to

varnish a* clean strip of tin, and after thorough drying

immerse it under water and note the rapidity and ex-

tent of corrosion and discoloration.

578. Toughness and elasticity. In order for a varnish

to be durable and give entire satisfaction, it must have

the desired toughness and elasticity as well as the

requisite hardness. A varnish which is brittle, althoughit may have the required hardness, will be easily

cracked or crushed by a very moderate blow. Somevarnishes are required to be tougher and more elastic

than others, as in the case of floor finishes.

579. The varnish having thoroughly dried on the

test glass alongside of the standard sample, its tough-

ness may be determined to a certain extent by its be-

havior under the thumb-nail, and the results obtained

compared with a similar -examination on the varnish

test board. "Also the films of the thoroughly dried


varnish on the test glass may then be scratched with a

sharp instrument. A small, sharply pointed knife-

blade is excellent for this purpose. A first-class var-

nish having suitable toughness and elasticity will show

a smooth, even scratch, no scaling or"dusting

"being

observable; and if the knife be held in the proper

position, a small, uniform, coherent ribbon of varnish

will be ploughed off. If the varnish is deficient in

elasticity and toughness, it will scale away under the

knife-point, exhibiting a ragged, irregular scratch.

Varnish films containing rosin when tested with the

knife-point will usually "dust" more or less badly, i.e.,

fly away from the knife-point in the form of a fine

powder, settling on the glass at a considerable distance

from the scratch. The fact that varnishes vary greatly

in consistency should be taken into account in makingthese tests, as the films on the glass will vary in thick-

ness according to the consistency of the varnish.

580. In judging the brittleness of a varnish on a

test board, especially if it is hardwood, the effect of the

material used for the first coat must be taken into con-

sideration. This may be readily shown by taking a

hardwood board, coating a portion of it with shellac,

another portion with an average cheap liquid filler,

and the remaining portion with the varnish itself.

A'fter applying two coats of varnish over the entire

surface and allowing it to harden thoroughly, it will be

found on testing the surface with a knife that the

varnish over the liquid filler is very brittle, that over

the shellac somewhat brittle, while the straight varnish-

filled surface will remain tough and elastic. Another

method of testing the elasticity is to varnish a strip of

tin, and, after thorough drying, bend the tin and note

the extent which the varnish gives under the strain to


which it is subjected. In making these various tests,

the chemist must be certain that the varnish is thor-

oughly dry, as many of the cheaper varnishes harden

slowly, and, if examined too soon, will show greater

toughness and elasticity than would be obtained in

actual practice.

581. Hardness. A varnish may have the toughnessand elasticity required of first-class goods, but may be

deficient in hardness. In order to report on the hard-

ness, the chemist should have some means of giving

this quality a numerical value. An instrument for

this purpose has been devised by Dr. A. P. Laurie and

F. G. Baily of Heriot Watt College, Edinburgh, the

essential features of which are a central rod sliding

easily in a vertical direction through holes in two

brackets. The upper portion of the rod has a screw

thread, on which is a running nut. By means of a

milled head at the top the rod is twisted round, and

the nut caused to travel up and down on the thread.

A spring is attached at its upper end to the travelling

nut at the lower end to the lower bracket. To the

lower end of the rod is attached a hardened blunt steel

point, and the varnished plate to be tested is placed

under this point, and the point brought to the surface

of the varnish. The test surface is drawn slowly under

the point, the pressure being increased until a white

scratch is observed, at which point the reading is

noted on the scale. The machine reads to a maxi-

mum of 2000 grams. Spirit varnishes break down at

a pressure of about 100 grams, rosjn varnishes 200 to

400 grams, fairly good common varnishes at about 700

grams, and fine carriage varnishes at 1200 grams and

upwards. The inventors claim that the best oil var-

nishes take twelve months to reach their maximum


hardness, and that the rate of drying and the ultimate

hardness can be measured with accuracy by their

instrument.

582. Classification of varnishes. The varnish indus-

try 'has from its beginning been conducted with as

much secrecy as possible, and but little has been pub-lished that would enable the average chemist to pass

judgment on the different grades and varieties of var-

nish, and for this reason a short discussion of some of

the principal classes of varnish may not be amiss.

583. Floor varnishes. Goods of this class should have

a medium consistency. If heavy they will require a

longer time to dry and harden than is desirable, and

would be apt to become marred from usage before

thoroughly hardened; if too thin they will not afford

the desired protection to the wood. In price they are

about the same as for first-class interior varnishes,

ranging usually from $2.00 to $2.50 per gallon whole-

sale. Floor varnishes are usually "long oil" goods, as

a high degree of elasticity is required.

584. Interior varnishes. Varnishes for interior workshould be of fairly heavy consistency, so as to stand

rubbing. For the best class of work they should be

"long oil," although "short oil" goods may be used

for the undercoats. In price they usually range from

$2.00 to $2.50 per gallon wholesale. Often, especially

in contract work, "No. 1 Coach" goods are used.

This term means absolutely nothing, as it stands for

no specific grade or quality of varnish. Sold under

this name varnishes are put on the market for $0.90 to

$1.10 per gallon, or even less, and are usually high in

rosin and benzine or heavier petroleum-products.

Polishing varnishes, such as are used for pianos, high-

class furniture, etc., are usually of excellent quality,


averaging in price from $2.50 to $2.75, although the

very best grades may run as high as $3.50 whole-

sale.

585. Interior varnishes being subjected to less stren-

uous usage than floor finishes, carriage or exterior

goods, the tendency has been to lower the standard of

quality, until perhaps low-grade, inferior goods are

the rule, and really high-grade finishes the exception,on the market at the present time. Neither is the

size of the company any guarantee that the product is

of high value, for many of the best grades of varnishes

are made by small concerns who depend on the qualityof their goods rather than on extensive advertising for

their sales.

586. Exterior varnishes. These should always be

"long oil" goods. Spar varnishes, which are the usual

type of exterior varnishes, should be of medium con-

sistency, tough and elastic, and not easily scratched.

In price they usually range from $3.00 to $3.75 per

gallon wholesale. Carriage varnishes bring the high-

est price of all varnishes, and their successful manu-facture is accomplished by only a comparatively small

number of concerns, and but few domestic brands are

rated equal to the best imported English goods.

Domestic carriage varnishes range from $4.75 to $5.75

wholesale, and the best imported English goods at about

$7.25 per gallon.

587. Short volume. It is a lamentable fact that

varnish manufacturers almost invariably defraud the

consumer by putting out their packages short in vol-

ume. Of eleven samples purchased by the author on

the open market, in the original package none were

full measure. The amount of shortage is given in the

following table:


Five per cent shortage in measure represents a veryfair profit to the manufacturer in itself.

588. Significance of lime in varnishes. The addition

of five to six per cent of quicklime to melted rosin

makes it considerably harder. The compound formed

easily dissolves in linseed oil (at the present time woodoil is largely used), and when properly thinned forms

the base of about all the cheap varnishes on the market.

Such varnishes are characterized by giving a brilliant

surface, easily scratched, and in a short time liable to

crack badly. The relation between the percentage of

lime (CaO) in the varnish and its toughness and elas-

ticity is not marked enough to enable the chemist to

pass judgment on its working qualities from the

amount of lime it contains.

589. Sixteen of the leading varnishes on the marketwere tested out for toughness and elasticity, and then

the amount of calcium oxide determined in each, the

results obtained being given in the following table.


590. Of twelve brands of floor varnishes examined bythe author, four were altogether too thin for the pur-

pose intended; and of fourteen interior finishes, four

were exceedingly thin, and several of the remainder

were below average in this respect.

Of a total of twenty-six of the leading brands of

floor, exterior and interior varnishes tested out bythe author, seven were considered first class in all

respects, eight were medium or just fair quality, while

eleven were unquestionably poor and inferior both as

regards working and the quality of the film after dry-

ing. Of the above eleven, eight were interior finishes.

591. The twenty-six with but two exceptions flashed

at room temperature, a fact which is worthy of consid-

erable attention on the part of the consuming public

as regards fire risk.

CHAPTER XXXIII.

VARNISH STAINS AND COLOR VARNISHES.

592. Varnish Stains. Such data as may be obtained

from an analysis of varnish stains is only of limited

value as they are essentially varnishes carrying a small

percentage of very finely ground colors, such as C. P.

chrome green, sienna-red toner, etc. The moderate

price at which these goods are offered, preclude the use

of high-priced varnishes, and in order to obtain the

desired effect usually a blend of two or more varnishes

is used. Some of the most successful varnish stains

are prepared by blending a straight China-wood-oil

rosin varnish with a short-oil kauri-rosin (two-thirds

low-priced kauri, one-third W. W. hardened rosin) var-

nish. Dark oak, light oak and walnut shades are ob-

tained by adding sufficient asphaltum-rosin varnish to

produce the desired effect; mahogany and rosewood by

using a red toner in connection with the asphaltum

black; light and deep cherry with raw sienna and red

toner and the various greens with C. P. chrome greenand small amounts of the asphaltum black.

These goods have been widely advertised during the

last few years under .various designations of which the

word "lac

"usually forms a part. The prevailing tend-

ency has been to use inferior rosin varnishes which

are not only brittle but scratch easily, showing the

customary"rosin streak/' A better class of goods

can be prepared by adding a long-oil kauri or manila

varnish to give elasticity.279


593. Color Varnishes. The varnish stains, above de-

scribed, possess two defects, they do not give clear,

transparent effects owing to the fact that the pigmentsthemselves are opaque. Also these pigments settle out

on standing and more or less trouble is experienced in

bringing them into uniform suspension when desired

for use. These difficulties have been overcome by the

use of colors soluble in the varnish such as the "fat

colors," so called, and certain organic lakes. These

afford a clean, transparent effect, and are easy to applybut they lack permanency of color. They are, however,

widely used.

594. Stain Finishes. These finishes are designed to

be applied over furniture or any interior finish, which

has already been fully varnished, in order to give a

mission, Flemish, Antwerp or similiar effect. In other

words the stain, in a measure, sinks into the already

applied varnish. These stains are prepared by dis-

solving various "fat colors," such as fat black, fat yel-

low, fat orange, fat red, fat brown, etc., in a combina-

tion of benzole, naphtha or petroleum spirits, and a

long-oil varnish. These fat colors can be secured from

any of the leading color supply houses and are aniline

colors combined with a fatty acid, like oleic or stearic

acid and sometimes rosin. While satisfactory to a

certain extent, these finishes are not very durable,

scratches showing badly because the color of the surface

of the wood has not been changed.

595. Oil-wood Stains. This class of goods is verysimiliar to varnish stains, except that in this case the

varnish is replaced by linseed oil. As found on the

market they will contain 15 to 25 per cent of a light-

colored boiled oil, and the balance naphtha or petroleum

spirits, except for the small amount of pigment present.

VARNISH STAINS AND COLOR VARNISHES. 281

The following analyses are characteristic of this class

of goods.i. ii. in.

Green, Cherry, Dark Oak,per cent. per cent. per cent.

Linseed oil . 14.. 16.4 18.0

Naphtha 79.0 77.4 75.0Chrome green 7.0Red toner 6.2

Asphaltum varnish 7. Ol

100.0 100.0 100.0

1 Obtained by comparison.

Some manufacturers use a mixture of boiled and rawoil in order to regulate the drying. The separation of

pigment and vehicle is best effected in a centrifuge.

CHAPTER XXXIV.

ENAMELS AND VARNISH SPECIALTIES.

596. Valuation. The essential consideration in the

analyses of enamels, enamel finishes and varnish paints

is the nature or composition of the vehicle which is

largely varnish. The pigments that may be present in

the above classes of products are of comparatively little

moment as their analysis and duplication are exceed-

ingly easy. The vehicle, on the other hand, offers manydifficulties as it is usually prepared by the blending of

two, three or even four varnishes of very diverse com-

positions and characteristics. The result being that

the blend thus obtained behaves very differently as re-

gards flowing, drying, toughness, hardness, etc., from

the component varnishes. These variations in be-

havior often take unexpected directions, as for example,two varnishes each of which may be comparatively slow

in drying, will,when mixed, dry quickly. It is, therefore,

not possible for an analysis, even if exact, of a varnish

to show anything of value as regards the physical or

working qualities. It will, however, serve to give an

approximate idea of the cost of the materials used, and

at about what price the varnish in question could be

duplicated. Having this information at hand, and a

suitable variety of varnishes of known composition and

properties to work with, it is not a difficult matter for

an experienced chemist to very closely duplicate the

various specialty products on the market. If the three

requisite conditions above enumerated are not ob-282

ENAMELS AND VARNISH SPECIALTIES. 283

tained the value of any results that may be secured

will be extremely uncertain.

597. Adoption of Analytical Methods. Recently con-

siderable progress has been made in the valuation of

varnish products by analysis and practically every var-

nish chemist has his own scheme which depends for its

success very largely on intuition, judgment and the

closeness with which he keeps in touch with the varnish

industry. It is, therefore, difficult, if not impossible, to

outline a scheme in print that can be followed and in-

telligent results obtained. The outline suggested byDr. Mcllhiney,

1if worked over carefully by the chemist

himself on varnish products of known composition, will

establish certain relative standards which together with

his own judgment and intuition will enable him to de-

termine approximately the composition.

598. Mcllhiney's Method. The oils and gums maybe examined by Mcllhiney's scheme as follows:

"The process, which is here described, depends uponthe fact that although the union between oil and hard

gum is too intimate to be broken up by the selective

solvent action of any solvent acting directly upon the

original mixture, the combination may be broken upand the oil and gum brought back to more nearly their

condition, before they were melted together, by sub-

mitting the mixture to the action of caustic potash in

alcoholic solution and subsequently acidifying the solu-

tion of potash salts so formed. By this means there

is obtained from hard-gum varnishes a quantity of guminsoluble in petrolic ether very closely approximatingthe amount of hard gum actually existing in the var-

nishes, while the linseed oil is represented by its fatty

acids which are readily soluble in this solvent unless

1Proceedings, Am. Soc. for Testing Materials, 1908.


they have been oxidized, in which case some of the

fatty acids of the linseed oil will accompany the insol-

uble hard gum."In carrying out the method an opportunity is given

to determine not only the weight of the oil and of gum,but also the Koettstorfer figure and the percentage of

glycerin in the mixture. All these data taken together

give a basis for corroborating the main figures.

599. "The process is carried out by weighing into an

Erlenmeyer flask 2 to 10 grams of the varnish, adding a

considerable excess of approximately half-normal solu-

tion of caustic soda or caustic potash in very strong or

absolute alcohol, distilling off the major portion of the

solvent, and redissolving in neutral absolute alcohol.

The solution is then titrated with a solution of pureacetic acid in absolute alcohol, approximately half-nor-

mal strength, to determine the amount of the excess of

alkali present. From this the Koettstorfer figure is de-

termined as the exact strengths of the acid and alkali

solutions have been ascertained independently by com- *

parison with known standards. A further quantity of

the standard solution of acid in alcohol is added so as

to exactly neutralize the total amount of alkali originally

added. By this means the acid bodies liberated from"

their combinations with alkali are obtained in solution

in strong alcohol. To this solution there is now added

a sufficient quantity of petrolic ether to dissolve the oil

acids and this petrolic ether, being miscible with the

strong alcohol, forms with it a homogeneous liquid.

Water is now added to the mixture in such .amount as

to so dilute the alcohol contained that it is no longer a

solvent for fatty or resin acids; this addition of water

causes the petrolic ether which was mixed with the alco-

holic liquid to separate, carrying with it the fatty acids.


The rosin goes with the fatty acids while the hard gum,

being insoluble in either the petrolic ether or in the very

dilute alcohol, separates in the solid state. The aque-

ous and ethereal layers are now separated in a sepa-

rating funnel and each is washed, the watery layer with

petrolic ether and the petrolic-ether layer with water.

The petrolic-ether layer is now transferred to a weighed

flask, the solvent distilled off and" the residue of fatty

acids and common rosin weighed. This latter is then

examined further by Twitchell's method to determine

the amount of rosin which it contains, or it may be ex-

amined qualitatively in a number of ways to establish

its identity.

600. "The aqueous layer is freed from the suspendedhard gum which it contains by filtering, and from anyfurther quantity of gum which the weak alcohol mayhave retained in solution by evaporating off the alcohol

and again filtering. The remaining aqueous liquid

contains the glycerin and this is determined by the

Hehner method with potassium bichromate the

method ordinarily used for examining spent soap lyes.

601. "The hard gum is according to this plan pre-

cipitated in such a way that it adheres to the sides of

the glass vessel in which the alcohol and petrolic-ether

mixture is diluted with water; the easiest method to

weigh it is, therefore, to carry on the operation of dilu-

tion in a weighed glass vessel and then to dry and weighthe hard gum in this vessel. It frequently happensthat some of the hard gum cannot be convenientlyretained in this vessel but that it must be filtered out ona weighed filter and the weight so found added to that

of the main portion.

602. "If the varnish contains non-volatile petroleumor other unsaponifiable matter it will naturally be in-


eluded in the fatty and resin acids, and it would be

necessary to saponify the latter and extract the un-

saponifiable matter from them while in the alkaline

state; this operation is so familiar to chemists that it

is mentioned here only to call attention to the necessityfor it in some cases.

603. "It would naturally be expected that on ac-

count of the well-known insolubility of the oxidized

fatty acids in petrolic ether, some of the acids of the

linseed oil which had been polymerized by heat duringthe cooking of the varnish, or which had been oxidized

during the blowing process to which some linseed oil is

subjected before making it up into varnish, would fail

to dissolve and would be counted in with the hard guminstead of with the linseed oil. It appears as a matter

of fact that this source of error is of slight importancein the case of oil thickened by heat but that the blow-

ing process gives an oil which is not completely ac-

counted for by the soluble fatty acids recovered. This

difficulty may be largely overcome by taking advantageof the greater solubility of the oxidized fatty acids in

alcohol as compared with the hard gum; the freshly

precipitated gum contaminated with oxidized fattyacids is treated with a moderate quantity of cold alco-

hol of about 85 per cent and allowed to digest for sometime. The soluble matter so extracted is then recov-

ered separately by evaporating off the alcohol.

604."Rosin when present is usually combined with

lime in the proportion of about 1 part of lime to 20 partsof rosin. An examination of the mineral constituents

of the varnish is, therefore, of some value. The extrac-

tion of the mineral bases may be effected by treating a

quantity of the varnish, somewhat thinned with ben-

zine, with strong hydrochloric acid, and examining the

aqueous liquid.


605. "The amount of fatty acids obtained repre-

sents about 92.5 per cent of the linseed oil. The identi-

fication of these fatty acids as belonging to linseed oil

or to china wood oil may be satisfactorily accomplishedin some cases, but there are undoubtedly many var-

nishes in which the analyst will be unable to identify

and determine the oils. The odor and physical char-

acteristics of the recovered gum are quite as importantas the known chemical tests of which the acidity and

the Koettstorfer figure are among the most important."

INDEX.

A. PAGEAcetic acid in white lead 99

Adulteration of turpentine 59

Aldehyde free alcohol 37

Agricultural paints 229

Aluminum silicate 86

Analysis of black pigments 185

Analysis of calcium carbonate pigments 82

Analysis of Chinese blue 206

Analysis of iron oxides 175

Analysis of leaded zincs 122

Analysis of petroleum thinners 75

Analysis of Prussian blue 204

Analysis of shellac varnish , 255

Analysis of white lead 92

Analysis of white paints 143

Analysis of zinc pigments ; 107

Antimony vermilion 220

Asphaltum varnish 268

B.

Barium carbonate 79

Barium sulphate 77

Barn paint 237

Barrel paste 229

Borax 21

Bromine value of oils 44

C.

Calcium carbonate 80

Calcium sulphate 84Carbon dioxide 97

Caustic soda 20

China wood oil 31

Chloride of lime 20Chrome yellow 211

Classification of varnishes 275

289

290 INDEX.

PAGECobalt blue 210

Cold-water paints 167

Combination emulsifiers 21

Composition of colored paints 170

Corn oil 28

Cottonseed oil . 27

Covered testers 54

Crack and crevice fillers 234

D.

Damar varnish 255

Detection of water in paints"

11

Dipping paints 232

E.

Enamels 282

Emulsions 17

Estimation of arsenic and antimony 117

Estimation of lead Ill

Estimation of mineral oil 25

Estimation of petroleum products 52

Estimation of rosin oil , 45

Estimation of water 12, 14

Estimation of wood alcohol 250

Excessive use of volatile oils 57

Evaporation test 46

F.

Fineness of pigments . 124

Fire test 56

Fish oil

'

28

Flash point 38

Flat wall finishes 138

Free fatty acids 36

Functions of turpentine 32

G.

Geer's modification 67

Gravity of pigments 127

H.

Heavy turpentine 68

Hexabromide test 47

INDEX. 291

! PAGEInert pigments 77

Iodine number 32

Iodine number of oils 35

Iron fillers 234

J.

Japans and driers 239

K.

Kalsomine 163

Koettstorfer number 36

L.

Labeling paint products 1

Lakes 165

Linseed oil constants 32

Linseed oil foots 41

Linseed oil specifications 47

Litharge 222

Lithopone 122

Long oil varnish 262

M.

Magnesium silicate 86

Metallic lead 94

O.

Oil from inferior seed 39

Oil reductions 137

Oil varnishes 257

Oleate of lead 19

Orange mineral 221

Op'en testers 56

P.

Paris white 80

Paste wood filler 91

Petroleum thinners 72

Practical testing of varnish 269

Practical testing of paint 129

Priming enamels 229

Priming ochres , 182

Prussian blue . . 204

292 INDEX.

R- PAGERatio of pigment to vehicle 10

Red lead 221

Rosin oil 29

Rough stuff 234

S.

Sandy lead 93

Saponification value 36

Separation of mineral oil 26

Separation of vehicle 5

Separation of volatile oils%. 23

Shade cloth paint 229

Shellac 245

Shellac varnish 247

Shingle stain 236

Short oil varnish 261

Silica 87

Soya-bean oil 30

Specific gravity 24

Spot test 24

T.

Thermometer correction 139

Tinting strength 126

Turpentine. 19, 59, 60, 62

Turpentine reductions 138

Typical analysis of mixed paints 157

U.

Uniform sample 4

Use of centrifuge 6

V.

Varnish stains 279

Vermilion 211

Vermilion primer 229

W.

Whiting 80

Wood fillers 223

Wood turpentine 63, 64, 67

Zinc sulphate 110

Zinc white . ,116

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Holley CD-Analysis of paint and varnish products red

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